Integral thermoelectric generator for wireless devices

ABSTRACT

Electrical power is produced by a first process component, a first heat pipe formed in part by a first cavity within the first process component, and a thermoelectric generator assembly. The thermoelectric generator assembly is thermally coupled on one side to a heat sink and on the other side to the first heat pipe. The first process component is in direct contact with a first process fluid and the first cavity is proximate the first process fluid. The thermoelectric generator assembly produces electrical power.

BACKGROUND

The present invention relates generally to wireless devices and, moreparticularly, to powering wireless devices in a wireless field devicenetwork.

Wireless devices are becoming prevalent in industrial applications. Ascomponents of wireless field device networks, wireless devices extendthe reach of control or process monitoring systems beyond that of wireddevices to locations where wiring may be difficult and expensive toprovide. A wireless field device network includes a cloud of wirelessdevices or nodes with a central controller or gateway. The nodes in thewireless network are able to both send and receive information.

Wireless field device networks are used to control and monitor disparateprocesses and environments. For example, wireless field device networksmay be used in oil fields. An oil field is composed of numerous discretelocations centered on well pads that are scattered over large areas.Communication between these isolated local areas is essential to theoverall management of the field. The wireless field device network at awell pad monitors and controls everything from flow rates, wellpressure, and fluid temperature to valve status and position andpotential leaks. The resulting data is relayed through the network tocontrollers that analyze the data and actuate control mechanisms inorder to manage production or prevent trouble.

A wireless field device network is a communication network made up of aplurality of wireless devices (i.e., nodes) organized in a wirelesstopology. Example of wireless topologies include mesh networks, such as,for example, WirelessHART®, and star networks such as, for example,Bluetooth®. In a wireless field device network, a wireless device is oneof a wireless transceiver, a wireless data router, and a wireless fielddevice. A wireless transceiver includes a transceiver and an antennaintegrated into a single device. A wireless data router includes awireless transceiver and a data router integrated into a single device.A wireless field device includes a wireless data router and a fielddevice integrated into a single device. A field device is afield-mounted device that performs a function in a control or processmonitoring system or plant monitoring system, including all devices usedin the measurement, control and monitoring of industrial plants,processes or process equipment, including plant environmental, healthand safety devices. A field device typically includes at least onetransducer, such as, for example, a sensor or an actuator, and mayperform a control or alert function. A wireless transceiver is a devicefor transmitting and receiving RF-based communication data. A datarouter is a device that routes data packets received by a wirelesstransceiver, unpacking the communication payload for consumption by anattached field device (if that device's address matches the finaldestination address in the packet) or redirecting the communicationpayload back to the wireless transceiver to be relayed back into thenetwork to the next destination in the logical path. For example, in awireless mesh network, because each wireless device must be capable ofrouting messages for itself as well as other devices in the network,each wireless device includes a data router. In contrast, in a simplestar network, where wireless devices need only to send and receivemessages, wireless devices need not include a data router.

The use of lower power RF radios is essential for wireless networksystems designed for transducer-based applications, such as a wirelessfield device network. Many devices in the network must belocally-powered because power utilities, such as 120V AC utilities orpowered data buses, are not located nearby or are not allowed intohazardous locations where instrumentation and transducers must belocated without incurring great installation expense. “Locally-powered”means powered by a local power source, such as a portableelectrochemical source (e.g., long-life batteries or fuel cells) or by alow-power energy-scavenging power source (e.g., vibration, solar, orthermoelectric). A common characteristic of local power sources is theirlimited power capacity, either stored, as in the case of a long-lifebattery, or produced, as in the case of a solar panel. Batteries areexpected to last more than five years and preferably last as long as thelife of the product.

SUMMARY

An embodiment of the present invention includes a first processcomponent, a first heat pipe formed in part by a first cavity within thefirst process component, and a thermoelectric generator assembly. Thethermoelectric generator assembly is thermally coupled on one side to aheat sink and on the other side to the first heat pipe. The firstprocess component is in direct contact with a first process fluid andthe first cavity is proximate the first process fluid. Thethermoelectric generator produces electrical power.

Another embodiment of the present invention is a method for generatingelectrical power for use in a wireless field device network. A processcomponent contacts a process fluid. Heat conducts between the processfluid and a surface of a sealed cavity within the process component.Heat transfers between the surface of a sealed cavity and athermoelectric generator assembly by the vaporizing and condensing of aworking fluid. Heat transfers between the thermoelectric generatorassembly and a heat sink by at least one of convection and conduction.Electrical power is generated from the conduction of heat through thethermoelectric generator assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1B illustrate a wireless field device incorporating the presentinvention mounted on a process flange.

FIGS. 2A-2F illustrate an embodiment of the present inventionincorporated into a thermowell for powering a wireless temperaturemeasurement field device.

FIGS. 3A-3C illustrate another embodiment of the present inventionincorporated into a thermowell for powering a wireless temperaturemeasurement field device.

FIGS. 4A-4C illustrate an embodiment of the present inventionincorporated into an averaging pitot tube for powering a wireless flowmeasurement field device.

FIGS. 5A-5F illustrate an embodiment of the present inventionincorporated into an orifice plate flange for powering a wireless flowmeasurement field device.

FIGS. 6A-6E illustrate an embodiment of the present inventionincorporated into a steam trap for powering a wireless data router.

FIGS. 7A-7E illustrate an embodiment of the present inventionincorporated into a Venturi tube for powering a wireless flowmeasurement field device.

FIGS. 8A-8F illustrate an embodiment of the present inventionincorporated into a pump housing for powering a wireless data router.

FIGS. 9A-9C illustrate an embodiment of the present inventionincorporated into an orifice plate for powering a wireless flowmeasurement field device.

FIG. 10 illustrates an embodiment of the present invention incorporatedinto each of two process components for powering a wireless flowmeasurement field device.

DETAILED DESCRIPTION

The present invention will be discussed in terms of powering wirelessdevices in a wireless field device mesh network. A person skilled in theart will recognize that the invention is equally suited to other networktopologies and is not limited to solely the embodiments described, butthat the invention will include all embodiments falling within the scopeof the appended claims.

The present invention powers wireless devices in a wireless field devicenetwork using thermoelectric power generation. As noted above, batteriesare expected to last more than five years and preferably last as long asthe life of the product. However, in some applications requiringfrequent communication, sensing, or actuation, batteries sufficient toprovide power for a reasonable length of time are prohibitively large.This is aggravated in severe climates where low temperatures limitbattery output or high temperatures limit battery lifetime. In locationswhere available solar radiation is very limited, for example, near theArctic Circle, solar panels also must be prohibitively large andexpensive to provide the necessary power. Often these applicationsinvolve process fluids at temperatures greatly above or below ambientconditions, suggesting the use of thermoelectric power generation.However, thermoelectric power generation is inherently inefficient.Significant improvement in the efficiency of thermoelectric powergeneration is essential to meet the energy requirements for a wirelessdevice in a wireless field device network.

The conversion efficiency of a thermoelectric generator is generallyless than 1% and is a function of the material and design of thethermoelectric generator. In addition, the amount of heat available tothe thermoelectric generator for conversion is greatly reduced by aseries of the thermal resistances between the source of the heat (orcold) and the surface of the thermoelectric generator. The thermalresistances slow the transfer of heat for a given cross-sectional areaperpendicular to the direction of heat flow, decreasing heat transferrate per area, or heat flux.

For example, a typical thermoelectric generator application is a hotfluid in a vessel (e.g., flowing through a pipe or contained within atank) surrounded by cooler air, with one side of a thermally conductiveelement attached to an external, uninsulated section of the vessel(strapping it on), and with the other side of the thermally conductiveelement in physical contact with one surface of a thermoelectricgenerator. A heat exchanger in contact with the ambient air is attachedto the other surface of the thermoelectric generator. There are threesignificant thermal resistances to the heat flux from the hot fluid inthe vessel to the thermoelectric generator: the vessel wall, thephysical contact (or lack of physical contact) between the thermallyconductive element and the vessel surface, and the thermal resistancethrough the thermally conductive element.

Vessel walls are generally made of materials with poor thermalconductivity such as, for example, iron (60 W/mK), stainless steel (10to 40 W/mK), or Hastelloy (10 W/mK). The heat flux must penetrate thefull thickness of the vessel wall to reach the thermally conductiveelement. Once the heat flux reaches the external vessel wall surface, itmust flow into the thermally conductive element. Attachment of such adevice to a curved vessel surface, such as a pipe or tank, is fraughtwith challenges. The radius of curvature of the thermally conductiveelement must match exactly that of the external vessel surface. Vesselsizes and surface textures vary dramatically making the required precisefit exceptionally difficult. A few point contacts between the two matingsurfaces must support virtually the entire heat flow across the area ofthe mating surfaces, with small air gaps (excellent insulators)occupying the bulk of the interface. The heat flow that does penetratethe vessel wall and cross the interface between the external vesselsurface and the thermally conductive element must then conduct throughthe thermally conductive element to reach the surface of thethermoelectric generator. Thermally conductive elements are typicallymade of a material with high thermal conductivity, for example, copper(400 W/mK), but still provide another thermal resistance to the heatflow, limiting the heat flux available to the thermoelectric generator.The present invention greatly reduces, or eliminates altogether, allthree series thermal resistances to heat flow from a process fluid to athermoelectric generator, significantly improving the heat fluxavailable for conversion by the thermoelectric generator.

The present invention provides power to a wireless device in a wirelessfield device network with a thermoelectric generator. The inventionincludes a process component directly contacting a process fluid.Process components that directly contact a process fluid include, forexample, thermowells, averaging pitot tubes, pipe flanges, orifice plateflanges, steam traps, pressure sensor remote seals, level switches,contacting radar level gauges, vortex flow meters, coriolis meters,magnetic flow meters, turbine meters, valve manifolds, flowstraightening elements, flow restrictors, control valves, shut-offvalves, filter housings, pump housings, and pressure relief valves. Theprocess component in the present invention contains a heat pipe formedin part by a heat collector cavity internal to the process component.The heat collector cavity is employed solely to form a portion of theheat pipe. The heat pipe couples to one side of the thermoelectricgenerator and a heat sink couples to the other side of thethermoelectric generator, transferring heat through the thermoelectricgenerator to generate electrical power for the wireless device. The heatpipe replaces the thermally conductive element describe above, greatlyreducing the thermal resistance associated with transferring heat to thesurface of the thermoelectric generator. Imbedding the heat pipe withina process component in direct contact with the process fluid eliminatesthe other two thermal resistances by penetrating the vessel walldirectly. The process component does not strap on to the vessel, butpenetrates or replaces a section of the vessel wall. Some thermalresistance remains from the need to conduct heat from the process fluidto the heat pipe cavity through the portion of the process componentseparating the heat collector cavity from the process fluid. However,because the heat flows into the heat pipe from the entire surface areaof the heat collector cavity and is transported by the heat ofvaporization from the entire internal heat collector cavity surface, theheat flux transported by the heat pipe is much higher.

FIGS. 1A-1B illustrate an embodiment of the present invention forpowering a wireless device in a wireless field device network comprisinga thermoelectric generator incorporated into a process component. FIGS.1A-1B illustrate a process component incorporating the present inventionmounted on a process flange. FIG. 1B is a portion of FIG. 1A enlarged tobetter illustrate details of the invention.

FIG. 1A shows process measurement or control point 10, includingwireless field device 12, process component 14, process flange 16,process piping 20 and wireless field device network 21. As shown in FIG.1B, wireless field device 12 comprises electronics housing 22, anelectronics circuit (not shown), antenna 24 and a transducer (notshown). Process component 14 is a flange-mounted component comprising athermoelectric generator assembly (not shown), heat transfer device 27,insulation 28 a, insulation 28 b, and a heat pipe (not shown). FIG. 1Balso shows a plurality of flange bolts 18. Although process piping 20 isillustrated as a pipe, it may also be any of a number of process vesselsincluding a process tank, storage tank, heat exchanger, boiler,distillation column, kiln, or reactor. Wireless field device network 21is any wireless field device network capable of wireless communicationwith wireless field device 12 and of communication with a control ormonitoring system. Wireless field device network 21 is, for example, awireless field device mesh network.

Process flange 16 is attached (generally welded) to an opening inprocess piping 20 to create a port into process piping 20. A sealinggasket (not shown), which is generally composed of material of lowthermal conductivity, is inserted between the mating surfaces of processcomponent 14 and process flange 16 before process component 14 isattached to the port to be in direct contact with process fluid F whenit flows through process piping 20. Process component 14 connects toprocess flange 16 with the plurality of flange bolts 18. Thethermoelectric generator assembly is integrated with process component14 and is indirectly in thermal contact with process fluid F. The heatpipe (not shown) thermally connects process fluid F and thethermoelectric generator. The thermoelectric generator assembly is alsoin thermal contact with heat transfer device 27 which is in thermalcontact with a heat sink, for example, ambient fluid A. Ambient fluid Asurrounds process measurement or control point 10 and is typically air.During normal operations, process fluid F and ambient fluid A are atdifferent temperatures. Insulation 28 a and insulation 28 b arepositioned to thermally shield heat transfer device 27 in thermalcontact with fluid A from portions of process component 14 in thermalcontact with fluid F. As shown in FIG. 1, process component 14 isphysically and electrically connected to wireless field device 12,providing an interface between the process fluid F and the transducer.Alternatively, electronics housing 22, antenna 24 and the electronicscircuitry of wireless field device 12 are physically separate from, butelectrically connected to, process component 14.

In operation, a heat flow driven by the temperature difference betweenprocess fluid F and ambient fluid A is transported by the heat pipe inprocess component 14. In the case where the temperature of process fluidF is higher than the temperature of ambient fluid A, the heat flow isfrom process fluid F located in process piping 20 to the thermoelectricgenerator assembly by way of the heat pipe. The heat flow is conductedthrough the thermoelectric generator assembly by the dissipation of theheat into ambient fluid A by heat transfer device 27, generatingelectrical power. The heat flow is in the opposite direction for thecase where the temperature of process fluid F is lower than thetemperature of ambient fluid A. The electrical power is conducted towireless device 12, providing power to wireless field device 12 for usein operating the transducer and for use in communicating with wirelessfield device network 21 through antenna 24. Parallel paths for heat flowbetween process fluid F and ambient fluid A that would tend tocircumvent the intended path through the thermoelectric generatorassembly are reduced by insulation 28 a and insulation 28 b.

All embodiments described below, except for the embodiment illustratedby FIG. 10, are for the case where the temperature of process fluid F ishigher than the temperature of the heat sink and the direction of heatflow is from process fluid F to the heat sink. It is understood that forall subsequently described embodiments, for the case where thetemperature of process fluid F is lower than the temperature of the heatsink, the description is the same, with only the direction of heat flowreversed, with heat flowing from the heat sink to process fluid F.

In all embodiments, a heat sink absorbs or carries away heat to maintaina steady heat flow through the thermoelectric element. For ease ofillustration, in all embodiments described below, except for theembodiment illustrated by FIG. 10, the heat sink is ambient fluid A.Ambient fluid A is often air, but it is understood that ambient fluid Amay be another type of fluid, such as a cooling fluid, a body of water,or a second process fluid in physical contact with a heat transferdevice. In addition, the heat sink may be earth or another large thermalmass, for example, a wall of a building, or an earthen berm.

Wireless field devices like that described in FIG. 1 can measure any ofa number of process characteristics such as, for example, pressure, flowvelocity, mass flow, pH, temperature, density, and conductivity; or canmonitor process equipment for such things as vibration, strain, orcorrosion; or can monitor a general plant environment for such things asfire and gas detection; or can locate the present position of workersand equipment. FIGS. 2A-2F illustrate an embodiment of the presentinvention for powering a wireless device in a wireless field device meshnetwork comprising a thermoelectric generator incorporated into aprocess component for powering a wireless temperature measurement fielddevice, where the process component is a thermowell. A thermowell is asturdy, protective sheath designed to accommodate and protect atemperature sensor from the harmful effects of a fluid undermeasurement, including vibration, impact, corrosion, and abrasion. Thetemperature sensor is inserted into the thermowell along its axis andthe thermowell is inserted into a process vessel containing the fluidunder measurement. Thermowells also provide an additional advantage ofpermitting replacement of a failed temperature sensor without having toshut down the process and open up the vessel.

FIG. 2A shows a cross-section of a thermowell incorporating the presentinvention. FIG. 2A shows process measurement point 110, includingwireless field device 112, thermowell 114, process flange 116, flangebolts 118 and process piping 120 containing process fluid F. A heat sinkis provided by ambient fluid A. Ambient fluid A surrounds processmeasurement point 110 and is typically air. Although process piping 120is illustrated as a pipe as in FIG. 1, it may also be any of a number ofprocess vessels including a process tank, storage tank, heat exchanger,boiler, distillation column, kiln, or reactor. Wireless field device 112comprises electronics housing 122, electronics circuitry 123, antenna124, and temperature probe 130. Temperature probe 130 comprisestemperature sensor 132 and temperature sensor wires 134. Temperaturesensor 132 is any sensor that varies an electrical characteristic inresponse to temperature changes, for example, a thermocouple or an RTD.Temperature sensor wires 134 are wires compatible with temperaturesensor 132, for example, thermocouple wire. Electronics circuitry 123comprises sensor circuitry 136, transmitter communication circuitry 138,transceiver 140, data router 142, power control circuitry 144, andenergy storage device 146. Sensor circuitry 136 processes sensor signalsand provides sensor excitation as is known in the art. Transmittercommunication circuitry 138 comprises communication circuitry forsending and receiving wired signals, for example, HART® data.Transceiver 140 is a device for transmitting and receiving RF-basedcommunication data, for example, WirelessHART data. Data router 142 is adevice that routes data packets. Power control circuitry 144 receivesincoming power and conditions it as necessary for use by the othercomponents of electronics circuitry 123. Energy storage device 146stores energy for use by the other components of electronics circuitry123 and is, for example, a primary battery, a rechargeable battery, asupercapacitor, or an energy storage capacitor as is known in the art.Thermowell 114 is a flange-mounted process component comprisingthermoelectric generator assembly 126, heat transfer device 127,insulation 128 a, insulation 128 b, thermowell cavity 148, and heat pipe150. Thermoelectric generator assembly 126 comprises thermoelectricelement 152, heat spreader 154, and power cable 158. Thermoelectricelement 152 is a device that produces voltage across the device and anelectric current through the device (when connected to an electricalload) when opposite sides of the device are held at differenttemperatures, for example, a semiconductor-based device of a type knownin the art made of a series of alternating n-type and p-typesemiconductors. Heat spreader 154 is a block of high thermalconductivity material, for example, copper, employed to even out theheat flux over the surface of thermoelectric element 152. Heat transferdevice 127 is any device for efficiently exchanging heat with ambientfluid A. As illustrated, heat transfer device 127 is a pin-fin heatexchanger made of a high thermal conductivity material, for example,copper, and is designed with large ratio of surface area to volume toenhance the transfer of heat. Insulation 128 a and insulation 128 b areany type of durable, thermally insulating structures compatible withambient fluid A. In this embodiment, heat pipe 150 includes fill port160, plug 162, heat collector cavity 164, heat transport pipe 166, andheat dissipater cavity 168. Plug 162 is any plug that seals, forexample, a threaded metal plug. Heat collector cavity 164 is thatportion of heat pipe 150 imbedded within the portion of thermowell 114that is in direct contact with process fluid F. Heat dissipater cavity168 is that portion of heat pipe 150 that is in direct contact withthermoelectric generator assembly 126. Heat transport pipe 166 is thatportion of heat pipe 150 connecting heat collector cavity 164 to heatdissipater cavity 168.

Process flange 116 is attached (generally welded) to an opening inprocess piping 120 to create a port into process piping 120. A sealinggasket (not shown) is inserted between the mating surfaces of thermowell114 and process flange 116 before thermowell 114 is inserted into theport to be in direct contact with process fluid F when it flows throughprocess piping 120 as shown in FIG. 2A. Thermowell 114 connects toprocess flange 116 at a flanged portion of thermowell 114 with aplurality of flange bolts 118 (typically four or more, two shown).Temperature probe 130 is inserted into thermowell cavity 148 such thattemperature sensor 132 is at or near the end of thermowell 114 furthestinto process fluid F. Temperature probe 130 is generally held in placeby a threaded connection near the end of temperature probe 130 oppositethat of temperature sensor 132. Temperature sensor wires 134 connecttemperature probe 130 to electronics circuitry 123 within electronicshousing 122 at sensor circuitry 136. Antenna 124 connects to electronicscircuitry 123 within electronics housing 122 at transceiver 140. Withinelectronics circuitry 123, sensor circuitry 136 connects to transmittercommunication circuitry 138. Transmitter communication circuitry 138connects to data router 142 which connects to transceiver 140. Powercontrol circuitry 144 connects to energy storage device 146, sensorcircuitry 136, transmitter communication circuitry 138, data router 142,and transceiver 140. Heat pipe 150 extends from heat collector cavity164, described below in reference to FIG. 2D, to heat transport pipe166, described below in reference to FIG. 2F, to heat dissipater cavity168, described below in reference to FIG. 2E. Plug 162 seals off fillport 160. Heat dissipater cavity 168 of heat pipe 150 connects tothermoelectric generator assembly 126 at heat spreader 154. Heatspreader 154 is intimately attached to one side of thermoelectricelement 152 and heat transfer device 127 is intimately attached to theother side of thermoelectric element 152, opposite heat spreader 154.Power cable 158 connects thermoelectric element 152 to electronicshousing 122 at power control circuitry 144. Insulation 128 a ispositioned in a gap between heat transfer device 127 and the externalsurface of thermowell 114, with insulation 128 a extending beyond theedges of heat transfer device 127 to insure good thermal isolation.Insulation 128 b is positioned in the space between heat transfer device127 and the flanged portion of thermowell 114 attached to process flange116. Thermowell 114 is physically and electrically connected to wirelessfield device 112, providing an interface between process fluid F andtemperature probe 130. Alternatively, electronics housing 122,electronics circuitry 123, and antenna 124 are physically separate from,but electrically connected to, temperature probe 130 and thermowell 114.

In operation, temperature sensor 132 varies an electrical characteristicin response to a change in the temperature of process fluid F. Thevariation in electrical characteristic is conducted via temperaturesensor wires 134 to sensor circuitry 136. Sensor circuitry 136translates the change in electrical characteristic into a temperaturemeasurement. Sensor circuitry 136 sends the temperature measurement totransmitter communication circuitry 138 which sends the temperaturemeasurement and any additional information (e.g., wireless field deviceID) over a wired link (not shown) to data router 142. Data router 142formats the information into a digital data packet along withinformation on a transmission destination and sends the digital datapacket to transceiver 140 for transmission into a wireless field devicemesh network via antenna 124.

In addition, as a member of the wireless field device mesh network,wireless field device 112 may also route data packets received from thewireless field device mesh network. Transceiver 140 receives digitaldata packets from the wireless field device mesh network via antenna 124and sends the digital data packets to data router 142. Data router 142routes the data packets received by transceiver 140, unpacking thecommunication payload for consumption by transmitter communicationcircuitry 138, if the device address of wireless field device 112matches the final destination address in the packet, or redirecting thedigital data packets back to transceiver 140 to be relayed back into thenetwork via antenna 124 to the next destination in the logical path.

At least a portion of the power for the temperature sensing and datatransmission described above is supplied in the embodiment of thepresent invention by the operation of thermoelectric generator assembly126 with a heat flow efficiently supplied by heat pipe 150. Heatcollector cavity 164 collects heat from process fluid F as describedbelow in reference to FIG. 2D. Heat transport pipe 166 transfers theheat from heat collector cavity 164 to heat dissipater cavity 168 asdescribed below in reference to FIG. 2F. At heat dissipater cavity 168,heat is transferred into heat spreader 154, (as described below inreference to FIG. 2E) which evens out the heat flux as the heat flowconducts through heat spreader 154 to thermoelectric element 152. As theheat flows through thermoelectric element 152, a voltage is generated asa function of the amount of heat flowing through thermoelectric element152, and current flows to wireless field device 112. The generation ofboth a voltage and a current produce electrical power. If heat is notremoved from the side opposite heat spreader 154, thermal equilibrium isquickly reached and heat flow ceases along with the power production.Continuous power production requires removing heat from the side of thethermoelectric element 152 opposite heat spreader 154. Heat transferdevice 127, with its large surface area, efficiently removes heat fromthe side of thermoelectric element 152 opposite heat spreader 154 byconduction to ambient fluid A. Ambient fluid A, through convection,conduction or a combination of the two, absorbs or carries away the heatfrom heat transfer device 127, thus maintaining the steady heat flowthrough thermoelectric element 152 necessary for continuous powerproduction. In this embodiment, insulation 128 a and insulation 128 breduce heat entering heat transfer device 127 from sources other thanthermoelectric element 152 by insulating areas likely to be at atemperature between process fluid F and ambient fluid A, such asexterior surfaces of thermowell 114 and process piping 120. Thisimproves the efficiency of thermoelectric generator assembly 126 bylimiting the heat to be removed by heat transfer device 127 mainly tothe heat flowing through thermoelectric element 152. Power produced bythermoelectric element 152 is conducted by power cable 158 to powercontrol circuitry 144. Power control circuitry 144 conditions the powerand distributes it as needed to sensor circuitry 136, transmittercommunication circuitry 138, data router 142, and transceiver 140 forthe temperature sensing and data transmission operations describedabove. Optionally, power in excess of the immediate requirements fortemperature sensing and data transmission operations is stored in energystorage device 146. Power stored in energy storage device 146 is tappedby power control circuitry 144 when temperature sensing and datatransmission operation requirements exceed the power immediatelyavailable from thermoelectric generator assembly 126, for example,during process start up or shut down when the temperature of processfluid F is lower than during normal process operation.

According to one embodiment, FIG. 2B is a cross-section of a portion ofthermowell 114 that is in direct contact with process fluid F. As shownin FIG. 2B, heat collector cavity 164 has a circular cross-section. Thetubular shape of heat collector cavity 164 is efficiently created by,for example, drilling. The tubular shape continues throughout heat pipe150, with the exception of heat dissipater cavity 168.

FIG. 2C illustrates one embodiment of a shape of heat dissipater cavity168. The circular cross-section of heat transfer pipe 166 terminates atthe edge of heat dissipater cavity 168. Heat dissipater cavity 168 is arectangular cavity matching the rectangular shape of heat spreader 154.This shape is also efficiently created by manufacturing methods know inthe art. Heat dissipater cavity 168 is comprised of interior surfaces ofthermowell 114 on five of six sides and of heat spreader 154 on theremaining side. FIG. 2C further illustrates the shape of heat transferdevice 127. Heat transfer device 127 wraps partially around the exteriorof thermowell 114 to increase the surface area of heat transfer device127. As mentioned above, insulation 128 a preferably fills the gapbetween the portions of heat transfer device 127 that extend beyondthermoelectric element 152 and the exterior of thermowell 114.Insulation 128 a extends beyond the edges of heat transfer device 127 inall directions to insure good thermal isolation from the exteriorsurfaces of thermowell 114, which are at a temperature between that ofprocess fluid F and ambient fluid A.

An essential element in the efficient operation of the embodiment shownin FIG. 2A is the operation of heat pipe 150. FIG. 2D illustrates theheat transport mechanism working to transfer heat from process fluid Finto heat pipe 150. FIG. 2D is a cross-section of a portion of heatcollector cavity 164. In this embodiment, heat pipe 150 furthercomprises working fluid 170 and wicking device 172. Working fluid 170 ispreferably present in heat pipe 150 in both liquid (L) and vapor (V)phases. Working fluid 170 is selected depending on the expectedoperating temperature range between that of process fluid F and ambientfluid A and is, for example, water, ammonia, methanol, or ethanol.Preferably, wicking device 172 is a material with sufficiently smallpores to exert significant capillary pressure on the liquid phase ofworking fluid 170 and easily wetted by working fluid 170, for example,sintered ceramic, metal mesh, metal felt, or metal foam. Alternatively,wicking device 172 comprises grooves in the side of heat pipe 150running the length of heat pipe 150, sized to provide the requiredcapillary pressure on the liquid phase of working fluid 170.

According to one embodiment, wicking device 172 lines the sides of heatcollector cavity 164 and contains working fluid 170 in L phase. Inoperation, heat H from process fluid F flows through the metal wallssurrounding heat collector cavity 164. L phase working fluid 170 in heatcollector cavity 164 absorbs the heat flow and changes to V phaseworking fluid 170 once the absorbed heat reaches the heat ofvaporization for working fluid 170. V phase working fluid 170 expandsout of wicking device 172 into the interior of heat collector cavity164, increasing the pressure in heat collector cavity 164 and driving Vphase working fluid 170 to flow out of heat collector cavity 164 intoheat transport pipe 166. Simultaneously, the vaporization of L phaseworking fluid 170 from wicking device 172 permits more L phase workingfluid 170 to flow into heat collector cavity 164 from heat transportpipe 166 driven by capillary pressure in wicking device 172. In thismanner, heat flows efficiently from process fluid F into and out of heatcollector cavity 164. Although the most efficient heat flow is throughthe thinnest portion of thermowell 114 separating heat collector cavity164 from process fluid F, conduction of heat throughout the portion ofthermowell 114 in contact with process fluid F provides heat to flowinto heat collector cavity 164 from all directions.

Pursuant to this embodiment, FIG. 2E illustrates the heat transportmechanism working to transfer heat from heat pipe 150 intothermoelectric generator assembly 126. FIG. 2E is a cross-section ofheat dissipater cavity 168 (and connection portion of heat pipe 166).Like heat collector cavity 164, heat dissipater cavity 168 contains Vphase working fluid 170 and is lined with wicking device 172, whichcontains L phase working fluid 170 (except for the small regioncomprising fill plug 162). Unlike heat collector cavity 164, workingfluid 170 in heat dissipater cavity 168 is cooled by the operation ofheat transfer device 127. In operation, V phase working fluid 170 in theinterior of heat dissipater cavity 168 condenses onto the coolersurfaces of heat spreader 154, changes to L phase working fluid 170 andreleases the heat of vaporization absorbed at heat collector cavity 164.The released heat H conducts into heat spreader 154 and throughthermoelectric element 152 to heat transfer device 127. L phase workingfluid 170 wets wicking device 172 and is driven out of heat dissipatercavity 168 into heat transport pipe 166 by capillary pressure in wickingdevice 172. Simultaneously, the condensation of V phase working fluid170 in heat dissipater cavity 168 reduces the pressure in heatdissipater cavity 168, providing a pressure differential to drive more Vphase working fluid 170 from heat transport pipe 166 into heatdissipater cavity 168. In this manner, heat flows efficiently from heatpipe 150 into thermoelectric generator assembly 126.

FIG. 2F illustrates one embodiment of a heat transport mechanism workingto transfer heat collected from heat collector cavity 164, asillustrated in FIG. 2D, to heat dissipater cavity 168, as illustrated inFIG. 2E. FIG. 2F is a cross-section of a portion of heat transport pipe166, which physically and thermally connects heat collector cavity 164and heat dissipater cavity 168. Like heat collector cavity 164 and heatdissipater cavity 168, heat transport pipe 166 contains V phase workingfluid 170 and is lined with wicking device 172, which contains L phaseworking fluid 170. Wicking device 172 in heat transport pipe 166connects to wicking device 172 in heat collector cavity 164 and wickingdevice 172 in heat dissipater cavity 168 in a continuous fashion suchthat condensing L phase working fluid 170 from heat dissipater cavity168 flows through heat transfer pipe 166 to heat collector cavity 164driven by capillary pressure in wicking device 172. Depending on themounting orientation of thermowell 114, the capillary pressure may workwith or against the force of gravity. The capillary pressure in wickingdevice 172 must be sufficient to overcome the pressure differentialbetween heat collector cavity 164 and heat dissipater cavity 168, inaddition to the capillary pressure necessary to overcome the force ofgravity, to drive a continuous source of L phase working fluid 170 toheat collector cavity 164. The interior of heat transfer pipe 166connects to the interiors of heat collector cavity 164 and heatdissipater cavity 168 in a continuous fashion such that V phase workingfluid 170 flows through the interior of heat transport pipe 166 fromheat collector cavity 164 to heat dissipater cavity 168 driven by thepressure differential caused by the vaporization of L phase workingfluid 170 in heat collector cavity 164 and the condensation of V phaseworking fluid 170 in heat dissipation cavity 168.

Pursuant to one embodiment, thermowell 114 is ideally assembled at afactory under precisely controlled conditions, ensuring consistent,reliable operation. This is in contrast to strapping or otherwisemounting a thermoelectric generator onto a vessel out in the field. Heatpipe 150 is preferably sealed under partial vacuum sufficient tomaintain an internal pressure near the vapor pressure of working fluid170 and to remove non-condensing gases, the presence of which wouldimpede the flow of V phase working fluid 170 and reduce the efficiencyof heat pipe 150. Working fluid 170 is loaded into heat pipe 150 throughfill port 160 and sealed under partial vacuum with plug 162, as shown inFIG. 2A.

The embodiment of the present invention shown in FIGS. 2A-2F greatlyimproves the heat flux available for conversion by the thermoelectricgenerator by imbedding a heat pipe within a thermowell in direct contactwith a process fluid. By penetrating the vessel wall directly, theproblem of thermal resistance through the vessel wall is eliminated asis the need to achieve a good thermal connection between thethermoelectric generator and the vessel wall. Also, because the heatflows into heat pipe 150 from the entire surface area of heat collectorcavity 164 and is transported by the heat of vaporization from theentire internal heat collector cavity surface, the heat transported byheat pipe 150 can be extremely high. Ultimately, the amount of heattransported is dependant on the area of heat collector cavity 164, thesize and efficiency of heat transfer device 127, and the difference intemperature between ambient fluid A and process fluid F. Finally,because the entire unit can be assembled and tested under carefullycontrolled conditions at a factory, performance is more consistent andefficient.

The tubular heat collector cavity shape illustrated in FIGS. 2A-2F isone of many possible shapes employed depending on the process componentand the amount of power to be generated. FIGS. 3A-3C illustrate anotherembodiment of the present invention incorporated into a thermowell forpowering a wireless temperature measurement field device. In FIGS.3A-3C, a cylindrical shaped heat collector cavity is combined with athermoelectric generator assembly containing two thermoelectricelements. The larger heat collector cavity, with its increased surfacearea, supplies much greater heat flow than the embodiment of FIGS.2A-2F. A significantly larger heat transfer device is also needed tosupport the greater heat flow. The greater heat flowing through the twothermoelectric elements produces significantly more power than theembodiment of FIGS. 2A-2F. The additional power is useful for wirelessdevices where, for example, more frequent transmissions are desired. Theadditional power is also useful for powering other elements of thewireless field device network, for example, a central controller, agateway; a remote telemetry unit or a backhaul radio that connects agateway to a higher-level network or host computer.

FIG. 3A shows a cross-section of another embodiment of the presentinvention incorporated into a thermowell for powering a wirelesstemperature measurement field device. Most of the components of theembodiment of FIG. 3A are identical to those described in reference toFIG. 2A-2F with reference numbers differing by 100. FIG. 3A showsprocess measurement point 210, including wireless field device 212,thermowell 214, process flange 216, flange bolts 218 and process piping220 containing process fluid F. A heat sink is provided by ambient fluidA. Wireless field device 212 is identical to wireless field device 112described above. Thermowell 214 is a flange-mounted process componentcomprising thermoelectric generator assembly 226, heat transfer device227, insulation 228 a, insulation 228 b, thermowell cavity 248, and heatpipe 250. Thermoelectric generator assembly 226 comprises twothermoelectric elements 252, two heat spreaders 254, and two powercables 258. Thermoelectric elements 252 are identical to thermoelectricelement 152 described above. As illustrated, heat transfer device 227 isidentical to heat transfer device 127 described above, except that itcompletely encircles thermowell 214. Heat pipe 250 comprises two fillports 260, two plugs 262, heat collector cavity 264, heat transport pipe266, and two heat dissipater cavities 268. Heat pipe 250 also comprisesa wicking device (not shown) and a working fluid present in both liquidand vapor phases (not shown); both wicking device and working fluid areas described above in reference to FIGS. 2D-2F. Employing two fill ports260 on opposites of heat pipe 250 provides for more efficient loading ofthe working fluid. Heat collector cavity 264 is that portion of heatpipe 250 imbedded within the portion of thermowell 214 that is in directcontact with process fluid F. Heat dissipater cavities 268 are thoseportions of heat pipe 250 that are in direct contact with thermoelectricgenerator assembly 226. Heat transport pipe 266 is that portion of heatpipe 250 connecting heat collector cavity 264 to heat dissipatercavities 268. Connections and operations of the embodiment shown in FIG.3A are as described above in reference to FIG. 2A, with componentnumbers increased by 100.

FIG. 3B is a cross-section of a portion of thermowell 214 that is indirect contact with process fluid F. As shown in FIG. 3B, heat collectorcavity 264 has a cylindrical cross-section. The cylindrical shape ofheat collector cavity 264 is efficiently created by manufacturingmethods known in the art. In this embodiment, the cylindrical shapecontinues throughout heat pipe 250, with the exception of heatdissipater cavities 268.

FIG. 3C is a cross-section of a portion of thermowell 214 containingheat dissipater cavities 268. The cylindrical cross-section of heattransfer pipe 266 terminates at the junction with heat dissipatercavities 268. Heat dissipater cavities 268 are identical to heatdissipater cavity 168 described above. FIG. 3C further illustrates theshape of heat transfer device 227. Heat transfer device 227 wrapscompletely around the exterior of thermowell 214. As with embodimentsdescribed above, insulation 228 a fills the gap between the portions ofheat transfer device 227 that extend beyond thermoelectric elements 252and the exterior of thermowell 214. Insulation 228 a extends beyond theedges of heat transfer device 227 to insure good thermal isolation fromthe exterior surfaces of thermowell 214.

The embodiment of the present invention shown in FIGS. 3A-3C greatlyimproves the heat flux available for conversion by the thermoelectricgenerator by imbedding a heat pipe within a thermowell in direct contactwith a process fluid. This embodiment, in addition to all of theadvantages described for embodiments above, is able to producesignificantly more power by increasing the size of both the heat pipeand the thermoelectric generator assembly. Although the embodiment isshown with two thermoelectric elements, it is understood that additionalthermoelectric elements can be added to produce additional power, solong as sufficient heat flow is produced.

As mentioned above, wireless field devices like that described in FIG. 1can measure any of a number of process characteristics such as, forexample, pressure, flow velocity, mass flow, pH, temperature, density,and conductivity; or can monitor process equipment for such things asvibration, strain, or corrosion; or can monitor a general plantenvironment for such things as fire and gas detection; or can locate thepresent position of workers and equipment. FIGS. 4A-4C illustrate anembodiment of the present invention for powering a wireless device in awireless field device mesh network with a thermoelectric generatorincorporated into a process component, where the process component is anaveraging pitot tube and the wireless device is a wireless flowmeasurement field device. An averaging pitot tube such as, for example,the Rosemount® 485 Annubar, measures flow velocity by sensing ram (high)and static (low) pressures caused by the fluid flowing past the pitottube. Increasing flow velocity produces a larger difference between thetwo pressures. The two pressures transmit through ports and plenums inthe pitot tube to a differential pressure sensor which directly measuresthe difference between the two pressures.

FIG. 4A shows a cross-section of an averaging pitot tube incorporatingone embodiment of the present invention. FIG. 4A shows processmeasurement point 310, including wireless field device 312, averagingpitot tube 314, process flange 316, flange bolts 318 and process piping320 containing process fluid F. A heat sink is provided by ambient fluidA. Ambient fluid A surrounds process measurement point 310 and istypically air. Although process piping 320 is illustrated as a pipe asin FIG. 1, it may also be any of a number of process vessels including aprocess tank, storage tank, heat exchanger, boiler, distillation column,kiln, or reactor. Wireless field device 312 comprises electronicshousing 322, electronics circuitry 323, antenna 324, and differentialpressure (DP) sensor 330. DP sensor 330 is any sensor or sensors thatvary an electrical characteristic ,in response to changes in thedifference between two simultaneously sensed pressures such as, forexample, the Rosemount 3051 S pressure transmitter. Electronicscircuitry 323 comprises sensor circuitry 336, transmitter communicationcircuitry 338, transceiver 340, data router 342, power control circuitry344, and energy storage device 346. Sensor circuitry 336 processessensor signals and provides sensor excitation as is known in the art.Transmitter communication circuitry 338 comprises communicationcircuitry for sending and receiving wired signals. Transceiver 340 is adevice for transmitting and receiving RF-based communication data. Datarouter 342 is a device that routes data packets. Power control circuitry344 receives incoming power and conditions it as necessary for use bythe other components of electronics circuitry 323. Energy storage device346 stores energy for use by the other components of electronicscircuitry 323 and is, for example, a primary battery, a rechargeablebattery, a supercapacitor, or an energy storage capacitor as is known inthe art. Averaging pitot tube 314 is a flange-mounted process componentcomprising thermoelectric generator assembly 326, heat transfer device327, insulation 328 a, insulation 328 b, high pressure plenum 332, lowpressure plenum 334, and heat pipe 350. Thermoelectric generatorassembly 326 comprises thermoelectric element 352, heat spreader 354,and power cable 358. Thermoelectric element 352 is a device thatproduces voltage across the device and an electric current through thedevice (when connected to an electrical load) when opposite sides of thedevice are held at different temperatures, for example, asemiconductor-based device of a type known in the art made of a seriesof alternating n-type and p-type semiconductors. Heat spreader 354 is ablock of high thermal conductivity material, for example, copper,employed to even out the heat flux over the surface of thermoelectricelement 352. Heat transfer device 327 is any device for efficientlyexchanging heat with ambient fluid A. As illustrated, heat transferdevice 327 is a pin-fin heat exchanger made of a high thermalconductivity material, for example, copper, and is designed with largeratio of surface area to volume to enhance the transfer of heat.Insulation 328 a and insulation 328 b are any type of durable, thermallyinsulating structure compatible with ambient fluid A. Heat pipe 350comprises fill port 360, plug 362, heat collector cavity 364, heattransport pipe 366, and heat dissipater cavity 368. Heat collectorcavity 364 is that portion of heat pipe 350 imbedded within the portionof averaging pitot tube 314 that is in direct contact with process fluidF. Heat dissipater cavity 368 is that portion of heat pipe 350 that isin direct contact with thermoelectric generator assembly 326. Heattransport pipe 366 is that portion of heat pipe 350 connecting heatcollector cavity 364 to heat dissipater cavity 368. Heat pipe 350further comprises a wicking device (not shown) and a working fluidpresent in both liquid and vapor phases (not shown); both wicking deviceand working fluid are as described above in reference to FIGS. 2D-2F.

Process flange 316 is attached (generally welded) to an opening inprocess piping 320 to create a port into process piping 320. A sealinggasket (not shown) is inserted between the mating surfaces of averagingpitot tube 314 and process flange 316 before averaging pitot tube 314 isinserted into the port to be in direct contact with process fluid F whenit flows through process piping 320 as shown in FIG. 4A. Averaging pitottube 314 connects to process flange 316 at a flanged portion ofaveraging pitot tube 314 with a plurality of flange bolts 318 (typicallyfour or more, two shown). DP sensor 330 is attached to averaging pitottube 314 such that a pressure in high pressure plenum 332 and a pressurein low pressure plenum 334 are simultaneously sensed by DP sensor 330.DP sensor 330 connects to electronics circuitry 323 within electronicshousing 322 at sensor circuitry 336. Antenna 324 connects to electronicscircuitry 323 within electronics housing 322 at transceiver 340. Withinelectronics circuitry 323, sensor circuitry 336 connects to transmittercommunication circuitry 338. Transmitter communication circuitry 338connects to data router 342 which connects to transceiver 340. Powercontrol circuitry 344 connects to energy storage device 346, sensorcircuitry 336, transmitter communication circuitry 338, data router 342,and transceiver 340. Heat pipe 350 extends from heat collector cavity364 to heat dissipater cavity 368 with heat transport pipe 366connecting heat collector cavity 364 to heat dissipater cavity 368. Plug362 seals off fill port 360 after the working fluid is loaded into heatpipe 350 under partial vacuum. Heat dissipater cavity 368 of heat pipe350 connects to thermoelectric generator assembly 326 at heat spreader354. Heat spreader 354 is intimately attached to one side ofthermoelectric element 352 and heat transfer device 327 is intimatelyattached to the other side of thermoelectric element 352, opposite heatspreader 354. Power cable 358 connects thermoelectric element 352 toelectronics circuitry 323 within electronics housing 322 at powercontrol circuitry 344. Insulation 328 a is positioned in a gap betweenheat transfer device 327 and the external surface of averaging pitottube 314, with insulation 328 a extending beyond the edges of heattransfer device 327 to insure good thermal isolation. Likewise,insulation 328 b is positioned in the space between heat transfer device327 and the flanged portion of averaging pitot tube 314 attached toprocess flange 316.

In operation, DP sensor 330 varies an electrical characteristic inresponse to changes in the difference between a pressure in highpressure plenum 332 and a pressure in low pressure plenum 334, the twopressures resulting from the flow of process fluid F past averagingpitot tube 314 as conducted by separate ports in the pitot tube to highpressure plenum 332 and low pressure plenum 334. The variation inelectrical characteristic is translated by sensor circuitry 336 into aflow measurement. Sensor circuitry 336 sends the flow measurement totransmitter communication circuitry 338 which sends the flow measurementand any additional information (e.g., wireless field device ID) over awired link (not shown) to data router 342. Data router 342 formats theinformation into a digital data packet along with information on atransmission destination and sends the digital data packet totransceiver 340 for transmission into a wireless field device meshnetwork via antenna 324.

In addition, as a member of the wireless field device mesh network,wireless field device 312 routes data packets received from the wirelessfield device mesh network. Transceiver 340 receives digital data packetsfrom the wireless field device mesh network via antenna 324 and sendsthe digital data packets to data router 342. Data router 342 routes thedata packets received by transceiver 340, unpacking the communicationpayload for consumption by transmitter communication circuitry 338, ifthe device address of wireless field device 312 matches the finaldestination address in the packet, or redirecting the digital datapackets back to transceiver 340 to be relayed back into the network viaantenna 324 to the next destination in the logical path.

At least a portion of the power for the flow measurement and datatransmission described above is supplied in the embodiment of thepresent invention by the operation of thermoelectric generator assembly326 with a heat flow efficiently supplied by heat pipe 350. Heatcollector cavity 364 collects heat from process fluid F. Heat transportpipe 366 transfers the heat from heat collector cavity 364 to heatdissipater cavity 368. At heat dissipater cavity 368, heat istransferred into heat spreader 354, which evens out the heat flux as theheat flow conducts through heat spreader 354 to thermoelectric element352. As the heat flows through thermoelectric element 352 a voltage anda current are generated as a function of the amount of heat flowingthrough thermoelectric element 352. The generation of both a voltage anda current produce power which is consumed by wireless field device 312as needed. Heat transfer device 327, with its large surface area,efficiently removes heat from the side of thermoelectric element 352opposite heat spreader 354 by conduction to ambient fluid A. Ambientfluid A, through convection, conduction or a combination of the two,absorbs or carries away the heat, thus maintaining the steady heat flowthrough thermoelectric element 352 necessary for continuous powerproduction. Insulation 328 a and insulation 328 b reduce heat enteringheat transfer device 327 from sources other than thermoelectric element352 by insulating areas likely to be at a temperature between processfluid F and ambient fluid A, such as exterior surfaces of averagingpitot tube 314. This improves the efficiency of thermoelectric generatorassembly 326 by limiting the heat to be removed by heat transfer device327 to the heat flowing through thermoelectric element 352. Powerproduced by thermoelectric element 352 is conducted by power cable 358to power control circuitry 344. Power control circuitry 344 conditionsthe power and distributes it as needed to sensor circuitry 336,transmitter communication circuitry 338, data router 342, andtransceiver 340 for the flow measurement and data transmissionoperations described above. Optionally, power in excess of the immediaterequirements for flow measurement and data transmission operations isstored in energy storage device 346. Power stored in energy storagedevice 346 is tapped by power control circuitry 344 when flowmeasurement and data transmission operation requirements exceed thepower immediately available from thermoelectric generator assembly 326,for example, during process start up or shut down when the temperatureof process fluid F is lower than during normal process operation.

FIG. 4B is a cross-section of a portion of averaging pitot tube 314 thatis in direct contact with process fluid F. High pressure plenum 332opens to ram (high) pressure, low pressure plenum 334 opens to static(low) pressure, and heat collector cavity 364 has a closed circularcross-section. In this embodiment, the tubular shape of heat collectorcavity 364 continues throughout heat pipe 350, with the exception ofheat dissipater cavity 368.

FIG. 4C illustrates the shape of heat dissipater cavity 368 according tothis embodiment. The circular cross-section of heat transfer pipe 366terminates at the edge of heat dissipater cavity 368. Heat dissipatercavity 368 is a rectangular cavity matching the rectangular shape ofheat spreader 354. This shape is also efficiently created bymanufacturing methods know in the art. Heat dissipater cavity 368 iscomprised of interior surfaces of averaging pitot tube 314 on five ofsix sides and of heat spreader 354 on the remaining side. FIG. 4Cfurther illustrates the shape of heat transfer device 327. Heat transferdevice 327 wraps partially around the exterior of averaging pitot tube314 to increase the surface area of heat transfer device 327. Asmentioned above, insulation 328 a fills the gap between the portions ofheat transfer device 327 that extend beyond thermoelectric element 352and the exterior of averaging pitot tube 314. Insulation 328 a extendsbeyond the edges of heat transfer device 327 in all directions to insuregood thermal isolation from the exterior surfaces of averaging pitottube 314, which are at a temperature between that of process fluid F andambient fluid A.

The embodiment of the present invention shown in FIGS. 4A-4C greatlyimproves the heat flux available for conversion by the thermoelectricgenerator by imbedding a heat pipe within an averaging pitot tube indirect contact with a process fluid. By penetrating the vessel walldirectly, the problem of thermal resistance through the vessel wall iseliminated as is the need to achieve a good thermal connection betweenthe thermoelectric generator and the vessel wall. Also, because the heatflows into heat pipe 350 from the entire surface area of heat collectorcavity 364 and is transported by the heat of vaporization from theentire internal heat collector cavity surface, heat can be veryefficiently transported by heat pipe 350.

The embodiments of the present invention described above compriseprocess components connected to a vessel by a process flange.Alternative embodiments of the present invention connect to a vessel byother than a process flange, for example, a threaded connection or awelded connection.

FIGS. 5A-5F illustrate yet another embodiment of the present inventionfor powering a wireless device in a wireless field device mesh networkwith a thermoelectric generator incorporated into a process component,where the process component is an orifice plate flange and the wirelessdevice is a wireless flow measurement field device. In contrast to theembodiments described above, this embodiment replaces a section ofprocess piping through which a process fluid (or process fluidby-product) flows, instead of attaching to an external opening in aprocess vessel. Orifice plate flanges such as those found in, forexample, a Rosemount® 1496 Flange Union, include pressure taps fortransmitting fluid pressure to a DP sensor. Two such orifice plateflanges comprise the flange union, with each orifice plate flangeemploying a pressure tap to transmit the fluid pressure in the pipe tothe DP sensor via an impulse line. An orifice plate, for example, aRosemount® 1495 Orifice Plate, positioned between the two orifice plateflanges causes a pressure drop across the orifice plate as the fluid isforced to flow through the orifice, resulting in two different fluidpressures being transmitted to the DP sensor. This pressure differenceis a function of flow velocity through the pipe. An increase in flowvelocity produces a larger difference between the two pressures. The twopressures transmit through the pressure taps and impulse lines to the DPsensor which directly measures the difference between the two pressures.

FIG. 5A illustrates one embodiment of a process component incorporatingthe present invention where the process component is an orifice plateflange. FIG. 5A shows process measurement or control point 410,including wireless flow measurement field device 412, orifice plateflange 414, orifice plate 415, orifice plate flange 416, stud/nuts 418and process piping 420 containing process fluid F. A heat sink isprovided by ambient fluid A. Ambient fluid A surrounds processmeasurement point 410 and is typically air. Wireless flow measurementfield device 412 comprises electronics housing 422, electronicscircuitry 423, antenna 424, differential pressure (DP) sensor 430,high-side (upstream) impulse line 432, and low-side (downstream) impulseline 434. Impulse line 432 and impulse line 434 are typically metalpipes chemically compatible with process fluid F, for example, stainlesssteel. Electronics circuitry 423 is as described above in reference toFIG. 4A with reference numbers increased by 100. Orifice plate flange414 is an in-line process component comprising high-side pressure tap433, thermoelectric generator assembly 426 (shown in FIG. 5B), heattransfer device 427, insulation 428, and heat pipe 450 (shown in FIG.5B). Thermoelectric generator assembly 426 comprises power cable 458.Orifice plate flange 416 is an in-line process component comprisinglow-side pressure tap 435. Together, orifice plate flange 414, orificeplate 415, orifice plate flange 416, studs/nuts 418, and sealing gaskets(not shown) comprise an orifice plate flange union.

Orifice plate flange 414 and orifice plate flange 416 are attached toprocess piping 420 at points W by, for example, welding. Orifice plate415 is inserted between orifice plate flange 414 and orifice plateflange 416 with a first sealing gasket between orifice plate 415 andorifice plate flange 414 and a second sealing gasket between orificeplate 415 and orifice plate flange 416. Orifice plate flange 414,orifice plate 415, orifice plate flange 416, and the two gaskets arebolted together by a plurality of stud/nuts 418. Thermoelectricgenerator assembly 426 is integrated with orifice plate flange 414 andis in thermal contact with process fluid F and ambient fluid A.Insulation 428 is positioned to thermally shield heat transfer device427 in thermal contact with fluid A from portions of orifice plateflange 414 in thermal contact with process fluid F. Impulse line 432connects to orifice plate flange 414 at pressure tap 433 by, forexample, a threaded connection. Similarly, impulse line 434 connects topressure tap 435. Impulse line 432 and impulse line 434 connect pressuretap 433 and pressure tap 435, respectively, to DP sensor 430, physicallyconnecting wireless flow measurement field device 412 to orifice plateflange 414 and orifice plate flange 416, respectively. DP sensor 430connects to electronics circuitry 423 within electronics housing 422 atsensor circuitry 436. Connections within electronics housing 422 are asdescribed above with respect to FIG. 4A.

In operation, high-side impulse line 432 and low-side impulse line 434transmit process pressures to DP sensor 430. DP sensor 430 varies anelectrical characteristic in response to changes in the differencebetween the pressure in high-side impulse line 432 and the pressure inlow-side impulse line 434, the two pressures resulting from therestricted flow of process fluid F through the orifice plate. Thevariation in electrical characteristic is translated by sensor circuitry436 into a flow measurement.

At least a portion of power for the flow measurement and datatransmission described above is supplied to wireless flow measurementfield device 412 in the embodiment of the present invention by theoperation of thermoelectric generator assembly 426 with a heat flowefficiently supplied by heat pipe 450 as described above in reference toFIG. 4A with reference numbers increased by 100 and illustrated in FIGS.5B-5F. A heat flow driven by the temperature difference between processfluid F and ambient fluid A is transported by heat pipe 450 in orificeplate flange 414. The heat flow is conducted through thermoelectricgenerator assembly 426 by the dissipation of the heat into ambient fluidA by heat transfer device 427, generating electrical power.

FIG. 5B is a cross-section of orifice plate flange 414 illustratingthermoelectric generator assembly 426, heat transfer device 427,insulation 428, and heat pipe 450. FIG. 5C is a portion of FIG. 5Benlarged to better illustrate the details of thermoelectric generatorassembly 426, heat transfer device 427, insulation 428, and a portion ofheat pipe 450. FIG. 5C shows primarily an extended portion of orificeplate flange 414 attached to the main, flange portion of orifice plateflange 414 by, for example, a threaded connection (as shown) or a weldedconnection. The extended portion of orifice plate flange 414 serves toprovide spatial separation for improved thermal isolation, in additionto the thermal shielding of insulation 428, between heat transfer device427 in thermal contact with fluid A and portions of orifice plate flange414 in thermal contact with process fluid F. As illustrated, heattransfer device 427 is a pin-fin heat exchanger made of a high thermalconductivity material, for example, copper, and is designed with largeratio of surface area to volume to enhance the transfer of heat.

As shown in FIGS. 5B-5C, thermoelectric generator assembly 426 comprisesthermoelectric element 452, heat spreader 454, and power cable 458.Thermoelectric element 452 and heat spreader 454 are as described inreference to FIG. 4A, with reference numbers differing by 100. Heat pipe450 comprises fill port 460, plug 462, heat collector cavity 464, heattransport pipe 466, and heat dissipater cavity 468. Heat collectorcavity 464 is that portion of heat pipe 450 imbedded within the portionof orifice plate flange 414 that is in direct contact with process fluidF. Heat dissipater cavity 468 is that portion of heat pipe 450 that isin direct contact with thermoelectric generator assembly 426. Heattransport pipe 466 is that portion of heat pipe 450 connecting heatcollector cavity 464 to heat dissipater cavity 468. Heat pipe 450further comprises a wicking device (not shown) and a working fluidpresent in both liquid and vapor phases (not shown); both wicking deviceand working fluid are as described above in reference to FIGS. 2D-2F.

Heat pipe 450 extends from heat collector cavity 464 to heat dissipatercavity 468 with heat transport pipe 466 connecting heat collector cavity464 to heat dissipater cavity 468. Heat dissipater cavity 468 of heatpipe 450 connects to thermoelectric generator assembly 426 at heatspreader 454. Heat spreader 454 is intimately attached to one side ofthermoelectric element 452 and heat transfer device 427 is intimatelyattached to the other side of thermoelectric element 452, opposite heatspreader 454. Power cable 458 connects thermoelectric element 452 toelectronics circuitry 423 within electronics housing 422 at powercontrol circuitry 444 (shown in FIG. 5A). Insulation 428 is positionedin a gap between heat transfer device 427 and the external surface oforifice plate flange 414, extending beyond the edges of heat transferdevice 427 to insure good thermal isolation between heat transfer device427 and the flange portion of orifice plate flange 414.

As illustrated in FIG. 5B, heat collector cavity 464 extends along muchof a portion of orifice plate flange 414 that is proximate process fluidF. FIG. 5D is a cross-section of orifice plate flange 414 showing thecylindrical shape of heat collector cavity 464. This shape surroundsprocess fluid F and provides a large surface area for heat transfer fromprocess fluid F into heat pipe 450.

FIG. 5E is another cross-section of orifice plate flange 414. FIG. 5Eillustrates orifice plate flange 414 rotated 90 degrees from FIG. 5B. Inaddition to the identically numbered elements in FIG. 5B, FIG. 5E showshigh side pressure tap 433 and plurality of bolt holes 474. Heattransfer device 427 extends significantly beyond thermoelectric element452 to provide a large ratio of surface area to volume to enhance thetransfer of heat with ambient fluid A. Insulation 428 is positioned inthe gap between heat transfer device 427 and the external surface oforifice plate flange 414, extending well beyond the edges of heattransfer device 427 to insure good thermal isolation between heattransfer device 427 and both the flange and extended portions of orificeplate flange 414.

FIG. 5F is another cross-section of orifice plate flange 414 in an axialplane 90 degrees from FIG. 5B. FIG. 5F shows high side pressure tap 433and heat collector cavity 464 of heat pipe 450. As shown in FIGS. 5B,and 5E-5F, heat pipe 450 is completely separate from, and does notinterfere with the functioning of, high side pressure tap 433.

Although the embodiment of FIG. 5A is described with orifice plateflange 414 positioned in the upstream location, it is understood that anorifice plate flange incorporating the present invention functions aswell when alternatively positioned in the downstream location. Inaddition, although the embodiment of FIG. 5A shows only orifice plateflange 414 incorporating the present invention to supply power towireless flow measurement field device 412, it is understood thatorifice plate flange 416 may also include the present invention in afashion identical to orifice plate flange 414. Such an arrangementincreases the power to wireless flow measurement field device 412 forapplications requiring, for example, more frequent communications withthe wireless field device mesh network. The additional power is alsouseful for powering other elements of the wireless field device network,for example, a central controller, a gateway; a remote telemetry unit ora backhaul radio that connects a gateway to a higher-level network orhost computer.

The embodiment of the present invention shown in FIGS. 5A-5F greatlyimproves the heat flux available for conversion by the thermoelectricgenerator by imbedding a heat pipe within an orifice plate flange indirect contact with a process fluid. By penetrating the vessel walldirectly, the problem of thermal resistance through the vessel wall iseliminated as is the need to achieve a good thermal connection betweenthe thermoelectric generator and the vessel wall. Also, because the heatflows into heat pipe 450 from the entire surface area of heat collectorcavity 464 and is transported by the heat of vaporization from theentire internal heat collector cavity surface, the heat flux transportedby heat pipe 450 is extremely high.

FIGS. 6A-6E illustrate yet another embodiment of the present inventionfor powering a wireless device in a wireless field device mesh networkwith a thermoelectric generator incorporated into a process component,where the process component is a steam trap and the wireless device is awireless data router. Like the embodiment described in reference toFIGS. 5A-5D, this embodiment replaces a section of process pipingthrough which a process fluid (or process fluid by-product) flows,instead of attaching to an external opening in a process vessel. FIG. 6Aillustrates a process component incorporating the present inventionwhere the process component is a steam trap. Steam trap 514 is attachedto process piping carrying primarily steam, steam line 516, atmeasurement or control point 510. Measurement or control point 510 is alocation where water condensing from the steam naturally collects.Measurement Or control point 510 includes wireless data router 512. Thecondensate water is a process fluid by-product resulting from heatlosses from steam line 516 into the ambient environment. Steam trap 514contains a device that permits the condensate water to flow out of steamline 516 and into process piping for draining condensate water,condensate line 520, while controlling, and largely preventing, theescape of steam into condensate line 520.

FIGS. 6B-6E illustrate how steam trap 514 shown in FIG. 6A embodies thepresent invention. FIG. 6B shows process measurement or control point510, including wireless data router 512, steam trap 514, steam line 516and condensate line 520. Wireless data router 512 comprises electronicshousing 522, electronics circuitry 523, and antenna 524. Electronicscircuitry 523 comprises transceiver 540, data router 542, power controlcircuitry 544, and energy storage device 546. Steam trap 514 comprisesthermoelectric generator assembly 526 (shown in FIG. 6E), heat transferdevice 527, insulation 528, steam trap bolts 518, and heat pipe 550(shown in FIGS. 6C-6E). Thermoelectric generator assembly 526 comprisespower cable 558. As illustrated, heat transfer device 527 is a pin-finheat exchanger.

Steam trap 514 is attached by, for example, threaded connections, tosteam line 516 and condensate line 520. Thermoelectric generatorassembly 526 is integrated with steam trap 514 and is in thermal contactwith steam/condensate F and ambient fluid A. Steam/condensate F is amixture of steam and condensate. A heat sink is provided by ambientfluid A. Steam/condensate F and ambient fluid A are at differenttemperatures. Power cable 558 connects thermoelectric generator assembly526 to electronics circuitry 523 within electronics housing 522 at powercontrol circuitry 544.

In operation, steam trap 514 permits condensate water from steam line516 to flow out of steam line 516 and into condensate line 520, asexplained below in reference to FIG. 6C. Wireless data router 512 routesdata packets received from a wireless field device mesh network. Atleast a portion of the power for this data transmission is supplied towireless data router 512 in the embodiment of the present invention bythe operation of thermoelectric generator assembly 526 with a heat flowefficiently supplied by heat pipe 550 as described in detail in FIGS.6C-6E below. A heat flow driven by the temperature difference betweensteam/condensate F and ambient fluid A is transported by heat pipe 550(shown in FIGS. 6C-6E) in steam trap 514. The heat flow is conductedthrough thermoelectric generator assembly 526 by the dissipation of theheat into ambient fluid A by heat transfer device 527, generatingelectrical power.

FIG. 6C is a cross-section of steam trap 514 illustrating a portion ofheat pipe 550, heat collector cavity 564. As shown in FIG. 6C, heatcollector cavity 564 lines the interior of steam trap 514 collectingheat from steam/condensate F. FIG. 6D is a cross-section of steam trap514 showing the cylindrical shape of heat collector cavity 564. Thisshape surrounds steam/condensate F flowing through steam trap 514 andprovides a large surface area for heat transfer from steam/condensate Finto heat pipe 550.

FIG. 6E is another cross-section of steam trap 514. FIG. 6E illustratessteam trap 514 rotated 90 degrees from FIG. 6C. In addition to theidentically numbered elements in FIG. 6C, FIG. 6E shows thermoelectricgenerator assembly 526 further comprises thermoelectric element 552, andheat spreader 554. Thermoelectric element 552 and heat spreader 554 areas described in reference to FIG. 4A, with reference numbers differingby 200. Heat pipe 550 comprises fill ports 560 a and 560 b, plugs 562 aand 562 b, heat collector cavity 564, heat transport pipe 566, and heatdissipater cavity 568. Heat collector cavity 564 is that portion of heatpipe 550 imbedded within the portion of steam trap 514 that is in directcontact with steam/condensate F. Heat dissipater cavity 568 is thatportion of heat pipe 550 that is in direct contact with heat spreader554 of thermoelectric generator assembly 526. Heat transport pipe 566 isthat portion of heat pipe 550 connecting heat collector cavity 564 toheat dissipater cavity 568. Heat pipe 550 further comprises a wickingdevice (not shown) and a working fluid present in both liquid and vaporphases (not shown); both wicking device and working fluid are asdescribed above in reference to FIGS. 2D-2F.

Heat pipe 550 extends from heat collector cavity 564 to heat dissipatercavity 568 with heat transport pipe 566 connecting heat collector cavity564 to heat dissipater cavity 568. Employing two fill ports on oppositesides of heat pipe 550 provides for more efficient loading of theworking fluid. Heat dissipater cavity 568 of heat pipe 550 connects tothermoelectric generator assembly 526 at heat spreader 554. Heatspreader 554 is intimately attached to one side of thermoelectricelement 552 and heat transfer device 527 is intimately attached to theother side of thermoelectric element 552, opposite heat spreader 554.Insulation 528 is positioned in a gap between heat transfer device 527and the external surface of steam trap 514, extending beyond the edgesof heat transfer device 527 to insure good thermal isolation betweenheat transfer device 527 and the exterior surfaces of steam trap 514.

Power for data transmission is supplied by the operation ofthermoelectric generator assembly 526 with a heat flow efficientlysupplied by heat pipe 550 as described above in reference to FIG. 4Awith reference numbers increased by 200. Although the embodiment ofFIGS. 6A-6E is described with a single thermoelectric generatorassembly, it is understood that a second thermoelectric generatorassembly, identical to the first, may be added to increase the poweravailable to the wireless data router for application requiring, forexample, more frequent communications with the wireless field devicemesh network.

The embodiment of the present invention shown in FIGS. 6A-6E greatlyimproves the heat flux available for conversion by the thermoelectricgenerator by imbedding a heat pipe within a steam trap in direct contactwith a flow of steam and condensate. By penetrating the steam trap walldirectly, the problem of thermal resistance through the steam trap wallis eliminated as is the need to achieve a good thermal connectionbetween the thermoelectric generator and the external surfaces of thesteam trap. Also, because the heat flows into heat pipe 550 from theentire surface area of heat collector cavity 564 and is transported bythe heat of vaporization from the entire internal heat collector cavitysurface, the heat flux transported by heat pipe 550 can be extremelyhigh.

FIGS. 7A-7E illustrate yet another embodiment of the present inventionfor powering a wireless device in a wireless field device mesh networkwith a thermoelectric generator incorporated into a process component,where the process component is a Venturi tube and the wireless device isa wireless flow measurement field device. As with the orifice plateflange and steam trap embodiments described above, this embodimentreplaces a section of process piping through which a process fluid (orprocess fluid by-product) flows, instead of attaching to an externalopening in a process vessel. A Venturi tube includes convergent anddivergent cone sections leading to and from a cylindrical section,respectively. The cylindrical section restricts fluid flow, resulting ina lower pressure in the cylindrical section as compared to a pressure atan inlet section. Venturi tubes such as those found in, for example, theDaniel® Venturi Tube, include two pressure taps, one at the inletsection and one at the cylindrical section for transmitting fluidpressure in the Venturi tube to a DP sensor via impulse lines. Thepressure differential relates to the flow rate through the Venturi tube,through the application of Bernoulli's equation. An increase in flowrate produces a larger difference between the two pressures. The twopressures transmit through the pressure taps and impulse lines to the DPsensor which directly measures the difference between the two pressures.

The embodiment shown in FIGS. 7A and 7B illustrates a process componentincorporating the present invention where the process component isVenturi tube. FIG. 7A shows process measurement or control point 610,including wireless flow measurement field device 612, Venturi tube 614,and process piping 620 containing process fluid F. A heat sink isprovided by ambient fluid A. Wireless flow measurement field device 612comprises electronics housing 622, electronics circuitry 623, antenna624, differential pressure (DP) sensor 630, high-side (upstream) impulseline 632, and low-side (downstream) impulse line 634 as described abovewith reference to FIG. 5A with reference numbers increased by 200. FIG.7B shows Venturi tube 614 of FIG. 7A rotated 90 degrees about the flowaxis. Venturi tube 614 is an in-line process component comprisinghigh-side pressure tap 633, low-side pressure tap 635, thermoelectricgenerator assembly 626 (shown in FIGS. 7C and 7E), heat transfer device627, insulation 628, and heat pipe 650 (shown in FIGS. 7C-7E).Thermoelectric generator assembly 626 comprises power cable 658. Asillustrated, heat transfer device 627 is a pin-fin heat exchanger.

Considering FIGS. 7A and 7B together, Venturi tube 614 is attached toprocess piping 620 at flanges W by, for example, welding or bolting.Thermoelectric generator assembly 626 is integrated with Venturi tube614 and is in thermal contact with process fluid F and ambient fluid A.Insulation 628 is positioned to thermally shield heat transfer device627 in thermal contact with fluid A from portions of Venturi tube 614 inthermal contact with process fluid F. Impulse line 632 connects toVenturi tube 614 at pressure tap 633 by, for example, a threadedconnection. Similarly, impulse line 634 connects to pressure tap 635.Impulse line 632 and impulse line 634 connect pressure tap 633 andpressure tap 635, respectively, to DP sensor 630, physically connectingwireless flow measurement field device 612 to Venturi tube 614.Connections within electronics housing 622 are as described in referenceto FIG. 5A above, with reference numbers increased by 200.

FIG. 7C is a longitudinal section of Venturi tube 614 illustratingthermoelectric generator assembly 626, insulation 628, and heat pipe650. Thermoelectric generator assembly 626 further comprisesthermoelectric element 652, and heat spreader 654. Thermoelectricelement 652 and heat spreader 654 are as described in reference to FIG.4A, with reference numbers differing by 300. Heat pipe 650 comprisesfill port 660, plug 662, heat collector cavity 664, heat transport pipe666, and heat dissipater cavity 668. Heat collector cavity 664 is thatportion of heat pipe 650 imbedded within the portion of Venturi tube 614that is in direct contact with process fluid F. Heat dissipater cavity668 is that portion of heat pipe 650 that is in direct contact withthermoelectric generator assembly 626. Heat transport pipe 666 is thatportion of heat pipe 650 connecting heat collector cavity 664 to heatdissipater cavity 668. Heat pipe 650 further comprises a wicking device(not shown) and a working fluid present in both liquid and vapor phases(not shown); both wicking device and working fluid are as describedabove in reference to FIGS. 2D-2F.

At least some power for the flow measurement and data transmission issupplied by the operation of thermoelectric generator assembly 626 witha heat flow efficiently supplied by heat pipe 650. Heat collector cavity664 collects heat from process fluid F. Heat transport pipe 666transfers the heat from heat collector cavity 664 to heat dissipatercavity 668. At heat dissipater cavity 668, heat is transferred into heatspreader 654, which evens out the heat flux as the heat flow conductsthrough heat spreader 654 to thermoelectric element 652. As the heatflows through thermoelectric element 652 a voltage and a current aregenerated as a function of the amount of heat flowing throughthermoelectric element 652. Power produced by thermoelectric element 652is conducted by power cable 658 to electronics circuitry 623 withinelectronics housing 622 at power control circuitry 644.

As illustrated in FIG. 7C, heat collector cavity 664 extends along muchof a portion of the cylindrical section of Venturi tube 614 thatdirectly contacts process fluid F. FIG. 7D is a cross-section of Venturitube 614 showing the cylindrical shape of heat collector cavity 664.This shape surrounds the flow of process fluid F and provides a largesurface area for heat transfer from process fluid F into heat pipe 650.

FIG. 7E is another cross-section of Venturi tube 614. In addition to theidentically numbered elements in FIG. 7C, FIG. 7E shows low sidepressure tap 635. Heat transfer device 627 extends significantly beyondthermoelectric element 652 to provide a large ratio of surface area tovolume to enhance the transfer of heat with ambient fluid A. Insulation628 is positioned in the gap between heat transfer device 627 and theexternal surface of Venturi tube 614, extending well beyond the edges ofheat transfer device 627 to insure good thermal isolation between heattransfer device 627 and the external surface of Venturi tube 614. Asshown in FIG. 7E, heat pipe 650 is completely separate from, and doesnot interfere with the functioning of low side pressure tap 635.

The embodiment of the present invention shown in FIGS. 7A-7E greatlyimproves the heat flux available for conversion by the thermoelectricgenerator by imbedding a heat pipe within a Venturi tube in directcontact with a process fluid. By penetrating the vessel wall directly,the problem of thermal resistance through the vessel wall is eliminatedas is the need to achieve a good thermal connection between thethermoelectric generator and the vessel wall. Also, because the heatflows into heat pipe 650 from the entire surface area of heat collectorcavity 664 and is transported by the heat of vaporization from theentire internal heat collector cavity surface, the heat flux transportedby heat pipe 650 is extremely high. Although the embodiment illustratedin FIGS. 7A-7E is a Venturi tube, it is understood to apply as well toother flow tube systems, for example, a magnetic flow meter tube and avortex tube.

FIGS. 8A-8F illustrate yet another embodiment of the present inventionfor powering a wireless device in a wireless field device mesh networkwith a thermoelectric generator incorporated into a process component,where the process component is a centrifugal pump and the wirelessdevice is a wireless data router. As with several of the previousembodiments described above, this embodiment replaces a section ofprocess piping through which a process fluid (or process fluidby-product) flows, instead of attaching to an external surface of aprocess vessel (clamp on). A pump is attached in series with processpiping carrying a process fluid to increase the velocity of the fluid orto increase the pressure of the process fluid by adding kinetic energyto the process fluid. Kinetic energy is supplied in, for example, acentrifugal pump, by a rotating impeller which employs centripetal forceto accelerate the process fluid in a radial direction.

The embodiment shown in FIGS. 8A-8C illustrates a process componentincorporating the present invention where the process component is apump. FIG. 8A shows process measurement or control point 710, includingwireless data router 712, pump 714, and process piping 720 containingprocess fluid F. A heat sink is provided by ambient fluid A. Wirelessdata router 712 comprises electronics housing 722, electronics circuitry723, and antenna 724 and is as described above in reference to FIG. 6Bwith reference numbers increased by 200. Pump 714 is an in-line processcomponent comprising thermoelectric generator assembly 726, heattransfer device 727, and insulation 728. As illustrated, heat transferdevice 727 is a pin-fin heat exchanger.

FIG. 8B is a cross-section of pump 714 showing that pump 714 furthercomprises heat pipe 750, impeller 780, motor 782, shaft 784, andbearing/seal 786. The internal components of motor 782 are omitted forclarity. FIG. 8B shows pump 714 rotated 90 degrees about axis of shaft784. FIG. 8C is a portion of FIG. 8B enlarged to better illustrate thedetails of thermoelectric generator assembly 726, insulation 728, and aportion of heat pipe 750. FIG. 8C shows an extended portion of pump 714attached to the main portion of pump 714 by, for example, a threadedconnection (as shown) or a welded connection. Thermoelectric generatorassembly 726 comprises thermoelectric element 752, heat spreader 754,and power cable 758 and is as described above in reference to FIG. 4Awith references numbers increased by 400. Heat pipe 750 comprises fillport 760, plug 762, heat collector cavity 764, heat transport pipe 766,and heat dissipater cavity 768. Heat collector cavity 764 is thatportion of heat pipe 750 imbedded within the portion of pump 714 that isin direct contact with process fluid F. Heat dissipater cavity 768 isthat portion of heat pipe 750 that is in direct contact withthermoelectric generator assembly 726. Heat transport pipe 766 is thatportion of heat pipe 750 connecting heat collector cavity 764 to heatdissipater cavity 768. Heat pipe 750 further comprises a wicking device772 and a working fluid present in both liquid and vapor phases (notshown); both wicking device 772 and working fluid are as described abovein reference to FIGS. 2D-2F. Impeller 780 is a generally frustoconicalshaped device with blades that accelerate process fluid F when impeller780 spins to produce increased velocity of, or higher pressure in,process fluid F as it exits pump 714. Motor 782 is any sort of motor,such as an electric motor. Shaft 784 is a durable, generallycylindrically shaped device for connecting motor 782 to impeller 780 tospin impeller 780. Bearing/seal 786 is a device that permits the passageand rotation of shaft 784 while largely preventing leakage of processfluid F past shaft 784.

Considering FIGS. 8A, 8B, and 8C together, pump 714 is attached toprocess piping 720 at flanges W by, for example, welding or bolting.Thermoelectric generator assembly 726 is integrated with pump 714 and isin thermal contact with process fluid F and ambient fluid A. Connectionswithin electronics housing 722 are as described in reference to FIG. 6Babove, with reference numbers increased by 200. Heat pipe 750 extendsfrom heat collector cavity 764 to heat dissipater cavity 768 with heattransport pipe 766 connecting heat collector cavity 764 to heatdissipater cavity 768. Heat dissipater cavity 768 of heat pipe 750connects to thermoelectric generator assembly 726 at heat spreader 754.Heat spreader 754 is intimately attached to one side of thermoelectricelement 752 and heat transfer device 727 is intimately attached to theother side of thermoelectric element 752, opposite heat spreader 754.

In operation, motor 782 spins impeller 780 via shaft 784, drawingprocess fluid F into pump 714, and accelerating process fluid F toproduce increased velocity of, or higher pressure in, process fluid F asit exits pump 714. Wireless data router 712 operates as described inreference to FIG. 6B above with reference numbers increased by 200.

At least a portion of the power for the operation of wireless datarouter 712 is supplied in the embodiment of the present invention by theoperation of thermoelectric generator assembly 726 with a heat flowefficiently supplied by heat pipe 750 as described above in reference toFIG. 4A with reference numbers increased by 400.

As illustrated in FIG. 8B, heat collector cavity 764 lines the interiorof pump 714 collecting heat from process fluid F as it is pumped throughpump 714 by impeller 780. FIGS. 8D-8F are axial cross-sections of pump714 further illustrating the shape of heat collector cavity 764. Takentogether, FIGS. 8B and 8D-8F show that heat collector cavity 764surrounds the interior of pump 714, except for openings necessary forthe inlet (FIGS. 8B and 8F), outlet (FIG. 8E), and seal/bearing 786(FIGS. 8B and 8D). By surrounding the interior of pump 714, a largesurface area is provided for heat transfer from process fluid F intoheat pipe 750.

The embodiment of the present invention shown in FIGS. 8A-8F greatlyimproves the heat flux available for conversion by the thermoelectricgenerator by imbedding a heat pipe within a pump in direct contact witha process fluid. By penetrating the pump wall directly, the problem ofthermal resistance through the pump wall is eliminated as is the need toachieve a good thermal connection between the thermoelectric generatorand the external surfaces of the pump. Also, because the heat flows intoheat pipe 750 from the entire surface area of heat collector cavity 764and is transported by the heat of vaporization from the entire internalheat collector cavity surface, the heat flux transported by heat pipe750 is extremely high. Although the embodiment of FIGS. 8A-8F isdescribed as a centrifugal pump, it is understood to apply to any typeof pump.

FIGS. 9A-9C illustrate yet another embodiment of the present inventionfor powering a wireless device in a wireless field device mesh networkwith a thermoelectric generator incorporated into a process component,where the process component is an orifice plate and the wireless deviceis a wireless flow measurement field device. Like some of theembodiments described above, this embodiment replaces a section ofprocess piping through which a process fluid (or process fluidby-product) flows, instead of attaching to an external opening in aprocess vessel. Orifice plates such as for example, a Rosemount® 1495Orifice Plate, positioned between two orifice plate flanges cause apressure drop across the orifice plate as the fluid is forced to flowthrough the orifice, resulting in two different fluid pressures beingtransmitted to the DP sensor, as described above in reference to FIGS.5A-5F.

FIGS. 9A-9C illustrate a process component incorporating the presentinvention where the process component is an orifice plate. FIG. 9A showsprocess measurement or control point 810, including wireless flowmeasurement field device 812, orifice plate flange 814, orifice plate815, orifice plate flange 816, stud/nuts 818 and process piping 820containing process fluid F. A heat sink is provided by ambient fluid A.Wireless flow measurement field device 812 comprises electronics housing822, electronics circuitry 823, antenna 824, RF cable 825, differentialpressure (DP) sensor 830, high-side (upstream) impulse line 832, andlow-side (downstream) impulse line 834. DP sensor 830, impulse lines 832and 834, and electronics circuitry 823 are as described above inreference to FIG. 5A, with reference numbers increased by 400. Orificeplate flange 814 and 816, such as those found in, for example, aRosemount® 1496 Flange Union, include high-side pressure tap 833 andlow-side pressure tap 835, respectively. Orifice plate 815 is an in-lineprocess component comprising thermoelectric generator assembly 826(shown in FIGS. 9B-9C), heat transfer device 827, insulation 828, andheat pipe 850 (shown in FIGS. 9B-9C). Together, orifice plate flange814, orifice plate 815, orifice plate flange 816, studs/nuts 818, andtwo sealing gaskets 821 (shown in FIG. 9B) comprise an orifice plateflange union. Thermoelectric generator assembly 826 comprises powercable 858. As illustrated, heat transfer device 827 is a pin-fin heatexchanger.

Orifice plate flanges 814 and 816 attach to process piping 820 at pointsW by, for example, welding. Orifice plate 815 is inserted betweenorifice plate flange 814 and orifice plate flange 816 with a sealinggasket 821 between orifice plate 815 and orifice plate flange 814 andanother sealing gasket 821 between orifice plate 815 and orifice plateflange 816. Orifice plate flange 814, orifice plate 815, orifice plateflange 816, and the two gaskets are bolted together by a plurality ofstud/nuts 818. Thermoelectric generator assembly 826 is integrated withorifice plate 815 and is in thermal contact with process fluid F andambient fluid A. Insulation 828 is positioned to thermally shield heattransfer device 827 in thermal contact with fluid A from portions oforifice plate 815 in thermal contact with process fluid F. Antenna 824is located remotely from electronics housing 822 and is connected toelectronics circuitry 823 by RF cable 825. All other connections are asdescribed above in reference to FIG. 5A, with reference numbersincreased by 400. Operation is also as described above in reference toFIG. 5A.

At least a portion of power for the flow measurement and datatransmission described above is supplied to wireless flow measurementfield device 812 in the embodiment of the present invention by theoperation of thermoelectric generator assembly 826 with a heat flowefficiently supplied by heat pipe 850 as described in detail in FIGS.9B-9C. A heat flow driven by the temperature difference between processfluid F and ambient fluid A is transported by heat pipe 850 in orificeplate 815. The heat flow is conducted through thermoelectric generatorassembly 826 by the dissipation of the heat into ambient fluid A by heattransfer device 827, generating electrical power.

FIGS. 9B and 9C are longitudinal and axial cross-sections, respectively,of orifice plate 815 illustrating thermoelectric generator assembly 826,insulation 828, and heat pipe 850. Considering FIGS. 9B and 9C together,thermoelectric generator assembly 826 comprises thermoelectric element852, heat spreader 854, and power cable 858. Thermoelectric element 852and heat spreader 854 are as described in reference to FIG. 4A, withreference numbers increased by 500. Heat pipe 850 comprises fill port860, plug 862, heat collector cavity 864, heat transport pipe 866, andheat dissipater cavity 868. Heat collector cavity 864 is that portion ofheat pipe 850 imbedded within the portion of orifice plate 815 that isin direct contact with process fluid F. Heat dissipater cavity 868 isthat portion of heat pipe 850 that is in direct contact withthermoelectric generator assembly 826. Heat transport pipe 866 is thatportion of heat pipe 850 connecting heat collector cavity 864 to heatdissipater cavity 868. Heat pipe 850 further comprises a wicking device(not shown) and a working fluid present in both liquid and vapor phases(not shown); both wicking device and working fluid are as describedabove in reference to FIGS. 2D-2F.

Heat pipe 850 extends from heat collector cavity 864 to heat dissipatercavity 868 with heat transport pipe 866 connecting heat collector cavity864 to heat dissipater cavity 868. Heat dissipater cavity 868 of heatpipe 850 connects to thermoelectric generator assembly 826 at heatspreader 854. Heat spreader 854 is intimately attached to one side ofthermoelectric element 852 and heat transfer device 827 is intimatelyattached to the other side of thermoelectric element 852, opposite heatspreader 854. Power cable 858 connects thermoelectric element 852 toelectronics circuitry 823 within electronics housing 822 at powercontrol circuitry 844 (shown in FIG. 9A).

Power for the flow measurement and data transmission is supplied by theoperation of thermoelectric generator assembly 826 with a heat flowefficiently supplied by heat pipe 850 as described above in reference toFIG. 4A with reference numbers increased by 500. As illustrated in FIGS.9B and 9C, heat collector cavity 864 extends along much of a portion oforifice plate 815 that is proximate process fluid F.

The embodiment of the present invention shown in FIGS. 9A-9C greatlyimproves the heat flux available for conversion by the thermoelectricgenerator by imbedding a heat pipe within an orifice plate in directcontact with a process fluid. By penetrating the vessel wall directly,the problem of thermal resistance through the vessel wall is eliminatedas is the need to achieve a good thermal connection between thethermoelectric generator and the vessel wall. Also, because the heatflows into heat pipe 850 from the entire surface area of heat collectorcavity 864 and is transported by the heat of vaporization from theentire internal heat collector cavity surface, the heat flux isefficiently transported by heat pipe 850. Finally, orifice plates aredesigned to be quickly and easily changed. Thus, an orifice plateembodying the present invention, such as that shown in FIGS. 9A-9C, caneasily replace an orifice plate not embodying the invention to supplypower to a wireless device.

All embodiments described above are shown with a heat transfer deviceillustrated as a pin-fin heat exchanger. However, it is understood thata heat transfer device is any device for efficiently exchanging heatwith ambient fluid A. Another example of a heat transfer device is afinned heat exchanger. Still another example of a heat transfer deviceis a device employing a second heat pipe in thermal contact with theside of the thermoelectric element opposite the heat spreader to furtherenhance the transfer of heat into the ambient fluid.

FIG. 10 illustrates an embodiment of the present invention incorporatedinto each of two process components for powering a wireless flowmeasurement field device. This embodiment differs from all embodimentsdescribed above in that, for each of the two process components, theheat sink is the process fluid in the other process component. Also, foreach of the two process components, the heat transfer device is theother process component's heat pipe. FIG. 10 is a cross-section oforifice plate flanges 914 a and 914 b. Orifice plate flanges 914 a and914 b are each identical in form and function to orifice plate flange414 as described in reference to FIGS. 5A-5F except for the followingdifferences. The extended portion of each orifice plate flange 914 a and914 b includes flange connection 988 a and 988 b, respectively. Inaddition, insulation 928 a and 928 b extend up the extended portion oforifice plate flange 914 a and 914 b only to flange connections 988 aand 988 b, respectively. Orifice plate flanges 914 a and 914 b sharethermoelectric generator assembly 926, which includes thermoelectricelement 952, first heat spreader 954 a, second heat spreader 954 b, andpower cable 958. Finally, the heat transfer device for orifice plateflange 914 a is heat pipe 950 b of orifice plate flange 914 b;similarly, the heat transfer device for orifice plate flange 914 b isheat pipe 950 a of orifice plate flange 914 a. The embodiment shown inFIG. 10 also comprises interface gasket 990, clamp gaskets 992, andclamps 994. Interface gasket 990 and clamp gaskets 992 are acompressible gasket material that is also a thermal insulator.

Orifice plate flanges 914 a and 914 b are connected at thermoelectricgenerator assembly 926, with heat pipe 950 a connecting tothermoelectric generator assembly 926 at heat spreader 954 a, and heatpipe 950 b connecting to thermoelectric generator assembly 926 at heatspreader 954 b. Heat spreader 954 a is in intimate contact with one sideof thermoelectric element 952 and heat spreader 954 b of thermoelectricgenerator assembly 926 in intimate contact with the other side ofthermoelectric element 952, opposite heat spreader 954 a. Power cable958 connects thermoelectric element 952 to a wireless device of any typeas shown in the previous embodiments. The connection between orificeplate flanges 914 a and 914 b supported by flange connections 988 a and988 b held together by clamp 994. Clamp gaskets 992, between clamp 994and flange connections 988 a and 988 b limit the flow of heat aroundthermoelectric element 952 via clamp 994. Similarly, interface gasket990, between flange connections 988 a and 988 b, limits the flow of heataround thermoelectric element 952 via flange connections 988 a and 988b.

As shown in FIG. 10, heat transfer pipes 966 a and 966 b of heat pipe950 a and 950 b, respectively, are formed of a flexible tube instead ofa rigid structure. This allows for easier connection of flangeconnection 988 a to flange connection 988 b than if the heat transferportions of each of heat pipe 950 a and 950 b were a rigid structure.The flexible tube is preferably a thin-walled metal tube, such as, forexample, an armored sleeve for a capillary-style seal connection for aRosemount® 1199 Diaphragm Seal System.

In operation, a heat flow is driven by the temperature differencebetween process fluid F1 in contact with orifice plate flange 914 a andprocess fluid F2 in contact with orifice plate flange 914 b, with, forexample, the temperature of process fluid F1 greater than thetemperature of process fluid F2. The heat flow is transported fromprocess fluid F1 by heat pipe 950 a in orifice plate flange 914 a toheat spreader 954 a. The heat flow is conducted through thermoelectricgenerator 952 to heat spreader 954 b by the transport of the heat flowfrom heat spreader 954 b by heat pipe 950 b to process fluid F2 inorifice plate flange 914 b. The conduction of the heat flow throughthermoelectric generator 952 generates electrical power, which isconducted over power cable 958 to a wireless device of any type as shownin the previous embodiments.

The embodiment of the present invention shown in FIG. 10 greatlyimproves the heat flux available for conversion by the thermoelectricgenerator by imbedding a heat pipe within each of two orifice plateflanges, each orifice plate flange in direct contact with a processfluid at a temperature different than that of the other orifice plateflange. By penetrating the vessel walls directly, the problem of thermalresistance through the vessel walls is eliminated as is the need toachieve a good thermal connection between the thermoelectric generatorand the vessel walls. In addition, the embodiment of FIG. 10 may producelarger and/or more controllable heat flows by control of thetemperatures of the process fluid in contact with each of the twoorifice plate flanges.

All embodiments above are described with a heat pipe that preferablyemploys a wicking device to permit operation of the heat pipe in allorientations. The wicking device permits movement of the denser liquidphase working fluid from the heat dissipater cavity to the heatcollector cavity regardless of the orientation of the heat pipe,including against the force of gravity. It is understood that for allembodiments, the wicking device may be omitted if the orientation of thedevice places the heat dissipater cavity above the heat collector cavitysuch that the vapor phase working fluid rises to the heat dissipatercavity and the liquid phase working fluid flows downward to the heatcollector cavity, the vapor phase working fluid being much less densethan the liquid phase working fluid.

In some embodiments above, the antenna is shown mounted to the exteriorof the electronics housing and electrically connected to thetransceiver. In other embodiments it is shown mounted remotely andconnected to the electronics housing by an RF cable or mountedcompletely within the electronics housing, for example, a componentmounted on a circuit board or a component integrated with a circuitboard. It is understood that any of the embodiments may employ any ofthese integrated antenna styles as desired.

As shown above in reference to FIG. 10, a heat transfer pipe of a heatpipe in the present invention may be formed of a flexible tube insteadof a rigid structure. Although illustrated only for the embodiment shownin FIG. 10, it is understood that in all of the embodiments, the heattransfer pipe of the heat pipe may be formed at least in part, by aflexible tube instead of a rigid structure. This may allow for easierconnection of a thermoelectric assembly to a heat transfer device for aparticular heat sink, such as large structure, for example, earth or anearthen berm. In addition, in the case of a heat transfer device thatis, for example, a pin-fin heat exchanger and the heat sink is, forexample, ambient air, a flexible tube structure permits easy adjustmentand orientation of the pin-fin heat exchanger for improved naturalconvection, resulting in improved performance of the heat transferdevice. Finally, employing a flexible tube structure for at least aportion of the heat transfer pipe of the heat pipe provides vibrationisolation between portions of the process component in contact with theprocess fluid and the thermoelectric generator assembly. Inhigh-vibration process environments, this enhances the reliability ofthe thermoelectric generator assembly.

The various embodiments provide power to a wireless device in a wirelessfield device network by employing a thermoelectric generatorincorporated into a process component. The process component directlycontacts a process fluid and contains a heat pipe formed in part by aheat collector cavity internal to the process component. The heatcollector cavity is employed solely to form a portion of the heat pipe.The heat pipe couples to one side of the thermoelectric generator and aheat sink couples to the other side of the thermoelectric generator,transferring heat through the thermoelectric generator to generateelectrical power for the wireless device. Imbedding the heat pipe withina process component in direct contact with the process fluid eliminatesthermal resistances by penetrating a vessel wall directly. Bypenetrating the vessel wall directly, losses associated with thermalresistance through the vessel wall are eliminated as is the need toachieve a good thermal connection between the thermoelectric generatorand the exterior wall of the vessel. In addition, because heat flowsinto the heat pipe from the entire surface area of the heat collectorcavity and is transported by the heat of vaporization from the entireinternal heat collector cavity surface, the heat flux transported by theheat pipe is extremely high. Finally, because a process componentincorporating the present invention can be assembled at a factory underprecisely controlled conditions, consistent, reliable operation is muchmore likely than with a thermoelectric generator strapped on to a vesselout in the field.

While the invention has been described with reference to an exemplaryembodiment(s), it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment(s) disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

1. An apparatus comprising: a first process component for directlycontacting a first process fluid, the first process component having afirst cavity proximate the first process fluid; a first heat pipe formedin part by the first cavity, the first heat pipe comprising a firstworking fluid; and a thermoelectric generator assembly; wherein thefirst heat pipe is thermally coupled to a first side of thethermoelectric generator assembly and a heat sink is thermally coupledto a second side of the thermoelectric generator assembly; wherein thethermoelectric generator assembly produces electrical power:
 2. Theapparatus of claim 1, further comprising a wireless transceiver, whereinthe electrical power produced by the thermoelectric generator assemblyat least partially powers the wireless transceiver.
 3. The apparatus ofclaim 2, further comprising a data router, wherein the electrical powerproduced by the thermoelectric generator assembly at least partiallypowers the data router.
 4. The apparatus of claim 1, further comprisinga transducer, wherein the electrical power produced by thethermoelectric generator assembly at least partially powers thetransducer.
 5. The apparatus of claim 1, further comprising an energystorage device for storing the electrical power.
 6. The apparatus ofclaim 1, wherein the first process component is one of a pipe flange, anorifice plate flange, an orifice plate, a thermowell, an averaging pitottube, a stream trap, a flow tube, a flow straightening element, acontrol valve, a shut-off valve, a pressure relief valve, a pressuremanifold, a valve manifold, a pump housing, a filter housing, a pressuresensor remote seal, a level switch, a contacting radar level gauge, avortex flow meter, a coriolis meter, a magnetic flow meter, a turbinemeter, and a flow restrictor.
 7. The apparatus of claim 1, wherein theheat sink is at least one of ambient air, water, a second process fluid,earth, a building, and an earthen berm.
 8. The apparatus of claim 1,wherein the first working fluid comprises at least one of water,ammonia, methanol, and ethanol.
 9. The apparatus of claim 1, wherein thefirst heat pipe is further formed in part by a flexible tube.
 10. Theapparatus of claim 1, wherein the first heat pipe further comprises awicking device.
 11. The apparatus of claim 10, wherein the wickingdevice is comprised of at least one of a sintered ceramic, metal mesh,metal felt, and metal foam.
 12. The apparatus of claim 10, wherein thewicking device is comprised of grooves on the interior surface of theheat pipe.
 13. The apparatus of claim 1, further comprising: a heattransfer device; and the thermoelectric generator assembly comprises: afirst heat spreader; and a thermoelectric element, wherein the firstheat spreader is attached to a first side of the thermoelectric elementto thermally couple the first side of the thermoelectric generatorassembly to the first heat pipe; and wherein the heat transfer devicethermally couples the heat sink to the second side of the thermoelectricgenerator assembly.
 14. The apparatus of claim 13, further comprisingthermal insulation between at least a portion of the first processcomponent and the heat transfer device.
 15. The apparatus of claim 13,wherein the heat transfer device comprises at least one of a pin-finheat exchanger and a finned heat exchanger.
 16. The apparatus of claim13, wherein: the thermoelectric generator assembly further comprises asecond heat spreader; the heat transfer device comprises a second heatpipe; and the second heat spreader is attached to a second side of thethermoelectric element to thermally couple the second side of thethermoelectric generator assembly to the second heat pipe.
 17. Theapparatus of claim 16, wherein the heat sink is a second process fluidand the heat transfer device further comprises: a second processcomponent for directly contacting the second process fluid, the secondprocess component having a second cavity proximate the second processfluid; wherein the second heat pipe is formed in part by the secondcavity, the second heat pipe comprising a second working fluid.
 18. Theapparatus of claim 17, wherein at least one of the first working fluidand the second working fluid comprises at least one of water, ammonia,methanol, and ethanol.
 19. The apparatus of claim 17, wherein at leastone of the first heat pipe and the second heat pipe is further formed inpart by a flexible tube.
 20. The apparatus of claim 17, wherein at leastone of the first heat pipe and the second heat pipe further comprises awicking device.
 21. The apparatus of claim 20, wherein the wickingdevice is comprised of at least one of a sintered ceramic, metal mesh,metal felt, and metal foam.
 22. The apparatus of claim 20, wherein thewicking device is comprised of grooves on the interior surface of theheat pipe.
 23. A system comprising: a wireless field device network; awireless device in wireless communication with the wireless field devicenetwork; and a first process component for directly contacting a firstprocess fluid, the first process component having a first cavityproximate the first process fluid; a first heat pipe formed in part bythe first cavity, the first heat pipe comprising a first working fluid;and a thermoelectric generator assembly, wherein the first heat pipe isthermally coupled to a first side of the thermoelectric generatorassembly and a heat sink is thermally coupled to a second side of thethermoelectric generator assembly; wherein the thermoelectric generatorassembly provides electrical power to the wireless device.
 24. Thesystem of claim 23, wherein the wireless device is one of a wirelesstransceiver, a wireless data router, and a wireless field device. 25.The system of claim 23, wherein the wireless field device networkcomprises a gateway, and wherein the thermoelectric generator assemblyprovides electrical power to the gateway.
 26. The system of claim 23,wherein the wireless field device network comprises at least one of aremote telemetry unit and a backhaul radio and wherein thethermoelectric generator assembly provides electrical power to at leastone of the remote telemetry unit and the backhaul radio.
 27. The systemof claim 23, wherein the process component is one of a pipe flange, anorifice plate flange, an orifice plate, a thermowell, an averaging pitottube, a stream trap, a flow tube, a flow straightening element, acontrol valve, a shut-off valve, a pressure relief valve, a pressuremanifold, a valve manifold, a pump housing, a filter housing, a pressuresensor remote seal, a level switch, a contacting radar level gauge, avortex flow meter, a coriolis meter, a magnetic flow meter, a turbinemeter, and a flow restrictor.
 28. The system of claim 23, wherein theheat sink is at least one of ambient air, water, a second process fluid,earth, a building, and an earthen berm.
 29. The system of claim 23,wherein the first working fluid is at least one of water, ammonia,methanol, and ethanol.
 30. The system of claim 23, wherein the firstheat pipe further comprises a wicking device.
 31. The system of claim30, wherein the wicking device is comprised of at least one of asintered ceramic, metal mesh, metal felt, and metal foam.
 32. The systemof claim 30, wherein the wicking device is comprised of grooves on theinterior surface of the heat pipe.
 33. The system of claim 23, furthercomprising: a heat transfer device; and the thermoelectric generatorassembly comprises: a first heat spreader, and a thermoelectric element,wherein the first heat spreader is attached to a first side of thethermoelectric element to thermally couple the first side of thethermoelectric generator assembly to the first heat pipe; and whereinthe heat transfer device thermally couples the heat sink to the secondside of the thermoelectric generator assembly.
 34. The apparatus ofclaim 33, further comprising thermal insulation between at least aportion of the first process component and the heat sink.
 35. The systemof claim 33, wherein the heat transfer device comprises at least one ofa pin-fin heat exchanger and a finned heat exchanger.
 36. The system ofclaim 33, wherein: the thermoelectric generator assembly furthercomprises a second heat spreader; the heat transfer device comprises asecond heat pipe; and the second heat spreader is attached to a secondside of the thermoelectric element to thermally couple the second sideof the thermoelectric generator assembly to the second heat pipe. 37.The system of claim 36, wherein the heat sink is a second process fluidand the heat transfer device further comprises: a second processcomponent for directly contacting the second process fluid, the secondprocess component having a second cavity proximate the second processfluid; wherein the second heat pipe is formed in part by the secondcavity, the second heat pipe comprising a second working fluid.
 38. Thesystem of claim 37, wherein at least one of the first working fluid andthe second working fluid comprises at least one of water, ammonia,methanol and ethanol.
 39. The system of claim 37, wherein the at leastone of the first heat pipe and the second heat pipe is further formed inpart by a flexible tube.
 40. The system of claim 37, wherein the atleast one of the first heat pipe and the second heat pipe furthercomprises a wicking device.
 41. The system of claim 40, wherein thewicking device is comprised of at least one of a sintered ceramic, metalmesh, metal felt, and metal foam.
 42. The system of claim 40, whereinthe wicking device is comprised of grooves on the interior surface ofthe heat pipe.
 43. A method for generating electrical power for use in awireless field device network, the method comprising: contacting aprocess component with a process fluid; conducting heat between theprocess fluid and a surface of a sealed cavity within the processcomponent; transferring heat between the surface of the sealed cavityand a thermoelectric generator assembly by vaporizing and condensing aworking fluid; conducting heat through the thermoelectric generatorassembly; transferring heat between the thermoelectric generatorassembly and a heat sink by at least one of convection and conduction;and generating electrical power from the conduction of heat through thethermoelectric generator assembly.
 44. The method of claim 43, whereinthe transferring heat between the surface of the sealed cavity and athermoelectric generator assembly further comprises wicking thecondensed working fluid toward the vaporizing working fluid.
 45. Themethod of claim 43, further comprising insulating the thermoelectricgenerator assembly from heat transfer with the process fluid other thanby condensing and vaporizing the working fluid.
 46. The method of claim43, further comprising powering at least partially a wireless devicewith the generated electrical power.